I am glad to meet you again, my dear readers. I am sure that many of you use the Internet, not only to search for entertaining content and interesting information, but also to communicate through Email.
In the process of configuring it, the question arises, which protocol do you want to use POP3 or IMAP. This is a really important parameter and I propose to understand the features of each of them.
What is postal protocol?
These are the rules, or order, in which communication occurs between objects, programs, and networks that are involved in the process of forwarding mail. In our case, the participants in this process are:
- Post service. This is a company that provides its server for storing correspondence, specialized software (including a website), as well as e-mail addresses to its customers. We are most interested in the mail server itself and the access settings to it. It should also be understood that an e-mail box implies the presence of an account and a space allocated for it (for storing messages) on the server;
- Mail client is a program for creating and processing mail. There are unique applications for mailboxes of one company. They can be successfully replaced by a corresponding mail web page, which allows you to operate mail directly on the server. There are also universal clients for working with accounts created on different services.
- Devices from which mail is accessed. It can be a PC, tablet, smartphone and even a push-button telephone with Internet access.
How does the mail delivery service work?
We will now look at how e-mail works, which will bring us closer to understanding the specifics of POP3 and IMAP. A user on his PC using an email client creates a letter that is sent to a certain email address. But it does not go directly to the recipient (even if he is at the next desktop), but only through the mail server. At the same time, it is convenient to track the correspondence path through conditional folders:
- from "Outgoing" on the sender's PC to "Outgoing" on the server in the sender's account;
- further, the transfer is carried out only on the server - from the “Outgoing” of the sender to the “Incoming” of the recipient's account;
- after connecting the addressee's device to the network with the mail client, the client starts exchanging data with the mail server. And now from the "Inbox" on the server, the letter goes to the same "Inbox" folder on the recipient's PC.
So, my friends. When organizing e-mail delivery along this route, there are two fundamentally different approaches.
- In one case, the main storage place for correspondence is the devices (mail clients) of the correspondents. And this order is called POP3 or Post Office Protocol version 3. It uses port 110.
- Another option is that all mail (including the files attached to it) is located on the mail server, and takes up physical space on it allocated for the user account. This order was referred to as IMAP (Internet Message Access Protocol). As you may have guessed, this technology is, in fact, analogous to cloud storage. Here the TCP protocol and port 143 are involved.
For the sake of fairness, it should be noted that POP3, with certain settings, allows the use of server space, but only for storing incoming letters. There is no such possibility for outgoing correspondence, because it is assumed that its sources are already on your device.
Now that we know how POP3 or IMAP works, I propose to consider their pros and cons in practical application. This will give us the answer to the question of what is best to use for your mailbox.
Home delivery
- All your correspondence is on your computer. Important documents and attachments are available to you regardless of your Internet connection. We will assume that in some cases this is exactly what the user needs;
- It is not difficult to guess that in this case the intensity of requests to the server is low. Moreover, the protocol itself was developed from the condition of minimizing the load on the network - the connection is made for a short time, only in order to move the server letters to the "client" or send them. And here we see an advantage that is relevant for the conditions of low-speed or limited Internet traffic - the data transmission channel is not overloaded and effectively performs its functions;
- Organizers of mail service also benefit from using POP. It becomes possible to minimize the amount of disk space used on servers, and accordingly reduce their number and maintenance costs.
The disadvantage of this protocol is obvious. Full-fledged work with mail is possible only from one device. For an office, this is somehow acceptable, but in other cases you need constant access from different devices and advanced capabilities when working with the server.
Our server is at your disposal, do whatever you want with your mail
Therefore, the IMAP protocol was developed as a more functional alternative. Let's evaluate its merits:
- I have already spoken about the fact that mail is in the cloud and is always available in the presence of the Internet. When your smartphone has at least 3G, and at home or in a cafe Wi-Fi, working with letters turns into a pleasure. Everything is always at hand. At the same time, just like on POP3, you can download correspondence from the server and save it on your PC or tablet.
- For the ability to search for letters (by name or address of the sender, as well as simply by individual words), the IMAP developers deserve special thanks from users whose mailboxes are constantly full, but have not been fully explored.
- You can easily operate on separate parts of letters and forward them to other recipients. In general, the ability to work with mail allows you to organize it into various categories, archive, and filter out spam.
- IMAP works well with different accounts.
- Messages can be marked with special flags that allow you to plan and organize work with incoming correspondence.
In fact, IMAP has much more capabilities, and it all depends on what you need. For example, to transfer a file from one device to another, I simply attach it to a draft, which is available to me from any gadget. But let's not get distracted and continue. I hope you have already decided what to choose for yourself, POP3 or IMAP, and now you need to know what to do next.
Where can I get the POP3 / IMAP settings?
And then you need to specify the appropriate parameters in the settings of the mail client. Usually you need to register the type of account (POP3 or IMAP), separate incoming and outgoing mail servers, user data, server port number and other parameters.
Fortunately, all well-known services such as Gmail, Yandex Mail, Microsoft Exchange support both protocols and provide relevant information on their websites. I think you can easily find it and handle the settings yourself.
The "discussion" about POP3 or IMAP is now over. All arguments are at your disposal, and I consider my mission accomplished.
On this I wish you all every success and say goodbye to you, my dear readers.
This article covers the most commonly used email protocols on the Internet - POP3, IMAP, and SMTP. Each of them has a specific function and way of working. The content of the article explains which configuration is best for the specific needs of the user when using an e-mail client. It also reveals the answer to the question of which protocol supports e-mail.
What is POP3?
Version 3 (POP3) is a standard postal protocol used to receive e-mail from a remote server to a local mail client. Allows you to download messages to your local computer and read them even when the user is offline. Please note that when you use POP3 to connect to your account, messages are downloaded locally and deleted from the email server.
By default, the POP3 protocol runs on two ports:
port 110 is the unencrypted POP3 port;
port 995 - this must be used if you want to securely connect to POP3.
What is IMAP?
Internet Messaging Access Protocol (IMAP) is an e-mail retrieval protocol that is used to access e-mail on a remote web server from a local client. IMAP and POP3 are the two most commonly used protocols for receiving emails and are supported by all modern email clients and web servers.
POP3 assumes that your email address is only accessible from one application, while IMAP allows you to log in from multiple clients at the same time. This is why IMAP is better if you are going to access your email from different places or if your messages are managed by multiple users.
IMAP runs on two ports:
Port 143 is the default unencrypted IMAP port.
port 993 - this must be used if you want to connect securely using IMAP.
What is SMTP?
Protocol is a standard protocol for sending e-mail over the Internet.
SMTP works on three ports:
port 25 is unencrypted by default;
port 2525 - it opens on all SiteGround servers if port 25 is filtered (for example by your ISP) and you want to send unencrypted emails using SMTP.
port 465 - This is used if you want to send messages securely using SMTP.
What are the protocols for e-mail exchange? Concepts and terms
The term "email server" refers to the two servers required to send and receive emails, that is, SMTP and POP.
The Incoming Mail Server is the server associated with your email account. There can be no more than one incoming mail server for it. To access incoming messages, you need an email client - a program that can receive email from an account, allowing the user to read, forward, delete, and reply to messages. Depending on your server, you can use a dedicated email client (such as Outlook Express) or a web browser. For example, Internet Explorer is used to access email-based accounts. Emails are stored on the incoming mail server until they are downloaded. Once you have downloaded your mail from the mail server, you will not be able to do it again. To download the data successfully, you need to enter the correct settings in your email program. Most of the incoming mail servers use one of the following protocols: IMAP, POP3, HTTP.
Outgoing mail server (SMTP)
This is a server used only for sending emails (for transferring them from your email client program to the receiver). Most outgoing mail servers use Protocol) to send mail. Depending on your network settings, the outgoing mail server may belong to your ISP or the server on which you set up your account. Alternatively, you can use a subscription based SMTP server that will allow you to send emails from any account. Due to spam issues, most outbound mail servers will not allow you to send emails unless you are logged into your network. An open relay server will allow you to use it to send emails, whether you belong to its network group or not.
Email ports
For networks, a port refers to the endpoint of a logical connection. The port number determines its type. The following are the default email ports:
POP3 - port 110;
IMAP - port 143;
SMTP - port 25;
HTTP - port 80;
secure SMTP (SSMTP) - port 465;
secure IMAP (IMAP4-SSL) - port 585;
IMAP4 over SSL (IMAPS) - port 993;
Secure POP3 (SSL-POP) - port 995.
Email protocols: IMAP, POP3, SMTP and HTTP
Basically, the protocol refers to the standard method used at each end of the communication channel. To deal with email, you must use a dedicated client to access the mail server. In turn, they can exchange information with each other using completely different protocols.
IMAP protocol
IMAP (Internet Messaging Access Protocol) is a standard protocol for accessing email from your local server. IMAP is a client / server protocol in which email is received and the data is stored by your internet server. Since it only requires a little data transfer, it works well even on slow connections, such as when connecting with a modem. When trying to read a specific email message, the client downloads data from the server. You can also create and manage folders or mailboxes on the server, delete messages.
POP3 protocol
Post Office Protocol 3 (POP) e-mail protocol provides a simple, standardized way for users to access mailboxes and download messages to their computers.
With POP, all your e-mails will be downloaded from the mail server to your local computer. You can also leave copies of your emails on the server. The advantage is that after downloading your messages, you can disconnect your internet connection and read your e-mail at your leisure without incurring additional communication costs. On the other hand, with this protocol, you receive and download a lot of unwanted messages (including spam or viruses).
SMTP protocol
The protocol is used by the Mail Transfer Agent (MTA) to deliver e-mail messages to a specific recipient server. SMTP can only be used to send emails, not to receive them. Depending on the settings of your network or Internet service provider, you may only use the SMTP protocol under certain conditions.
HTTP protocols
HTTP is not a protocol designed for email communication, but it can be used to access your mailbox. It is also often referred to as web email. It can be used to compose or receive emails from your account. Hotmail is a good example of using HTTP as the email protocol.
Managed file transfers and networking solutions
Your ability to send and receive email is mainly due to three TCP protocols. These are SMTP, IMAP and POP3.
SMTP
Let's start with SMTP because its main function is different from the other two. SMTP, or Simple Mail Transfer Protocol, is mainly used to send email from an email client (such as Microsoft Outlook, Thunderbird, or Apple Mail) to an email server. It is also used to relay or forward mail messages from one mail server to another. This is necessary if the sender and the recipient have different email providers.
SMTP, which is specified in RFC 5321, uses port 25 by default. It can also use port 587 and port 465. The latter, which was introduced as the port of choice for secure SMTP (a.k.a. SMTPS), is deprecated. But in reality, it is still used by several postal service providers.
POP3
The Post Office Protocol, or POP, is used to retrieve e-mail messages from the latest version that is widely used is version 3, hence the term "POP3".
POP version 3 specified in RFC 1939 supports extensions and several authentication mechanisms. Authentication features are required to prevent attackers from gaining access to user messages.
The POP3 client receives email as follows:
connects to the mail server on port 143 (or 993 for SSL / TLS connections);
retrieves email messages;
serves to connect before closing the mail client application and download messages on demand.
connects to the mail server on port 110 (or 995 for SSL / TLS connections);
deletes copies of messages stored on the server;
disconnects from the server.
Although POP clients can be configured so that the server can continue to store copies of downloaded messages, the steps above are common practice.
IMAP
IMAP, especially the current version (IMAP4), is a more complex protocol. This allows users to group related messages and place them in folders, which in turn can be organized hierarchically. It also features message flags that indicate whether a message has been read, deleted, or received. It even allows users to search server mailboxes.
Operation logic (imap4 settings):
Please note that messages are not deleted on the server. This can have serious consequences. The IMAP specifications can be found in RFC 3501.
Choosing between IMAP and POP3
Since the basic function of SMTP is fundamentally different, the dilemma of choosing the best protocol usually involves only IMAP and POP3.
If storage space on the server is important to you, then choose POP3. A server with limited memory is one of the main factors that can make you support POP3. Because IMAP leaves messages on the server, it can consume memory space faster than POP3.
If you want to access your mail at any time, then IMAP is the best choice. There is one good reason why IMAP was designed to store messages on a server. It is used to search for messages from multiple devices - sometimes even simultaneously. So if you have an iPhone, Android tablet, laptop, and desktop and want to read email from any or all of these devices, then IMAP is your best bet.
Synchronization is another benefit of IMAP. If you're accessing your email messages from multiple devices, chances are you'll want them all to reflect whatever actions you've taken.
For example, if you read messages A, B, and C, you want them to be marked as “read” on other devices as well. If you deleted letters B and C, then you want the same messages to be deleted from your mailbox on all gadgets. All of these syncs can only be achieved if you are using IMAP.
Because IMAP allows users to organize messages in a hierarchical order and place them in folders, it helps users to better organize their correspondence.
Of course, all IMAP functionality comes at a price. These solutions are more difficult to implement, and ultimately the protocol consumes a lot more CPU and RAM, especially when it is performing the synchronization process. In fact, high CPU and memory usage can happen on both the client side and the server side if there are a ton of messages to sync. From this point of view, the POP3 protocol is less expensive, although less functional.
Privacy is also one of the concerns that will be highly dependent on end users. They would generally prefer to download all emails and not leave copies of them on an unknown server.
Speed is an advantage that varies and depends on the situation. POP3 has the ability to download all email messages when connected. And IMAP can, if necessary (for example, with insufficient traffic), download only message headers or certain parts and leave attachments on the server. Only when the user decides that the remaining parts are worth downloading will they become available to him. Therefore, IMAP can be considered faster.
However, if all messages on the server have to be downloaded every time, then POP3 will work much faster.
As you can see, each of the described protocols has advantages and disadvantages. It's up to you to decide which features or capabilities are more important.
Also, the preferred way to access the e-mail client determines the preference of the protocol. Users with only one machine and using webmail to access their new emails will appreciate POP3.
However, users who exchange mailboxes or access their emails from different computers will prefer IMAP.
Spam firewalls with SMTP, IMAP and POP3
Most spam firewalls only deal with and protect SMTP. The servers send and receive SMTP email and they will be checked by the spam firewall at the gateway. However, some spam firewalls provide the ability to protect POP3 and IMAP4 when external users need these services to access their email.
SMTP firewalls are transparent to end users; there are no configuration changes for clients. Users still receive and send email messages to the email server. For example, Exchange or Dominos must configure proxy-based message routing to the firewall when sending e-mail, as well as provide the ability to send mail from the firewall.
IMAP is fantastic if you use the same email account across multiple devices like your computer, mobile phone, laptop, and web interface. Whenever you read an email on one device that syncs with the IMAP server and then syncs with all other devices and is marked as read on each device.
POP3, on the other hand, downloads mail to the client and then (typically) deletes it from the server. So that means, if you receive an email while you're out and about on your cell phone and read it, you won't receive it on your desktop PC.
here is a short tutorial I wrote years ago on how email, SMTP, POP3, IMAP, Webmail works ...
what is the standard?
a standard is a set of rules that all developers around the world follow. Some standards include HTTP, SMTP, POP3, ... White papers that describe each individual standard and most standards have been around for 0 to 30 years.
Each standard document has a very detailed explanation of what the standard is and how it works. Usually an RFC number is associated with a standard, but there are many different types of standards.
protocols
SMTP and POP3 are "standards". Each standard describes a separate protocol. A protocol is any kind of communication between two or more computers.
what is SMTP?
SMTP is a "standards" protocol used to send e-mail. Your computer uses SMTP to send email. see RFC 821, Aug 1982
what is POP3?
POP3 usually connects to a mail server and downloads messages to your computer. It can then additionally remove the message from the server (which is usually customizable).
how email works
- user A wants to send an email to user B.
- the user writes a letter and clicks send.
- User A's computer uses SMTP communication to send e-mail to User A (yes a, not b) SMTP server.
- User A's SMTP server, sends an email to User B's SMTP server using SMTP communication.
- user B, when he feels like this, contacts his SMTP server and uses POP3 to download messages.
some important notes:
the only way to send an email is to use SMTP. (You can actually use MAPI and some other stuff as well, but let's not talk about that)
the only way to get email is to use POP3. (Actually there is also IMAPv4, but we'll pretend that POP3 is the only way)
How Email Apps work:
SMTP communication is present on your computer, no matter which email client you are using. Every time an email message is sent, the computer uses SMTP to send the email message. It doesn't matter if you use Eudora, Outlook, Outlook Express, Mozilla Thunderbird, or a bespoke program. All programs use SMTP to send email.
by using standards, you ensure that you even know that user A is using Outlook and user B is using Eudora, and they both have different SMTP servers, both of the users will be able to communicate.
what is HTTP?
Before I can get to what webmail is, you first need to know what HTTP is. HTTP is another standard protocol. But HTTP is for downloading files and web pages, as opposed to SMTP, which is for sending email. See HTTP 1.1 RFC 2616, June 1999.
what is email?
webmail is a web page that allows HTTP to be used to send and receive emails.
but wait a minute, didn't I say that the only way to send email is using SMTP?
Yes! The web page provides you with a form that you fill out. Your computer does not know that it is different from the form you fill out to enter your credit card information, or the form you fill out to enter your home address, or the form you fill out to enter another website. All your computer knows is that you fill out the form.
when the Submit button is clicked, the web browser submits the form to the server. The server knows this form is for email though. Thus, the server interprets the form and retrieves the information it needs. The HTTP server then uses SMTP to send the message. Because the only way a message is going to get from user A to user B is using SMTP.
What did the web browser trick you into thinking that you are sending email. But what actually happens is that your web browser fills out the form and then the web server uses SMTP to send your email.
can you give me an email to walk through?
- user A wants to send email to user B, user A will use webmail.
- User A uses his browser to enter an Internet address (for example: www.hotmail.com).
- User a's computer uses HTTP to communicate with the server and ask for a web page that is used for web mail in this case.
- the server responds (using HTTP) on the user's computer and from a web page that gives him the ability to create mail, check mail, ...
- user A clicks on the compose post link. Again, user a's computer uses HTTP to communicate with the server.
- the server responds (using HTTP) to the user's computer from a web page (which contains a form), which allows the user to compose a message.
- user A fills in a webpage and clicks submit. The page is sent back to the server over HTTP.
- in the background, unknown to user A, the web server uses SMTP to send email to user B. why? Because the only way to send an email is to use SMTP
- the server responds (using HTTP) to the user's computer from a web page that says the email has been sent.
how is the SMTP web server used?
Since SMTP is a standard protocol, it uses SMTP just like any program would use SMTP. See How Email Works.
what is IMAPv4?
I mentioned IMAPv4 earlier. IMAPv4 is the second method used by email clients to receive your emails. IMAPv4 is also referred to more simply as IMAP. IMAPv4 is more complex than POP3, but gives you the ability to work on your email from multiple computers. If you are using more than one computer and you would like to access email from both computers, IMAP is the way to go.
IMAP stores all of its data on the mail server. Thus, each mail client from different computers can be synchronized. When reading an e-mail message from one computer, the work computer will also see that the message has been read. Since the data is stored on a server, IMAP email accounts are generally more expensive.
both standard Internet protocols (RFC 1064 IMAP4-RFC 1939 POP3) for receiving email from a mail server. Most email clients implement these protocols.
IMAP("Internet Message Access Protocol") allows you to organize your emails in folders * on a server that can synchronize with your email client. IMAP also synchronizes the "read" flag and other properties of the e-mail message (if it was a reply, forwarding etc.)
POP3("Post Office Protocol") mails are downloaded from one mailbox and are usually deleted after downloading, depending on the client settings.
you can't use IMAP or POP3 to send emails, that's what SMTP is for.
* folders in the IMAP specification are called "mailboxes".
POP3 (Post Office Protocol version 3) is a protocol used to receive e-mail messages from a server. The POP3 protocol was created due to the design of the e-mail system, it requires a server to host the e-mail as long as it is accepted by the recipient.
IMAP (Internet Message Access Protocol) is a standard protocol for accessing e-mail from a server. IMAP allows users to select the email message they want to take, make a folder on the server, look for specific email messages, even deleted email messages on the server. This ability is much better than POP (Post Office Protocol), which only allows receiving / downloading all messages without exception.
Currently, there are a lot of methods of communication via the Internet. You can use ICQ or Skype, social networks, and other resources. About two decades ago, the only way to send or receive a virtual letter was via email.
Until a certain time, the servers that process user emails had limited capabilities. Storing large amounts of information was expensive, which meant deleting a message from disk as soon as it was downloaded to the client's computer. Progress has gone ahead, there are more opportunities, the user can store letters in the mailbox on the central server for an unlimited amount of time, carry out various operations with them.
Data transfer protocols used when working with e-mail
A certain style is inherent in any form of communication - a set of agreements. On the network, it is a protocol. When working with E-mail, a number of protocols can be used. Among them:
- POP3;
- IMAP.
What is the difference, which protocol is appropriate and in which case it is advisable to use?
What is POP3
Wanting to send a letter or trust a personal mailbox located on a remote server, the user can use the browser installed on the computer, which is not very convenient. It is more often used, which exchanges information with the server using a certain protocol. If it is Post Office Protocol, the process is as follows:
- Compound;
- The client receives information about the state of the mailbox, downloads letters;
- Server update and deletion of selected messages;
- Closing the connection.
What is IMAP
IMAP provides the user with more options. After authorization on the mail resource, only message headers are downloaded to the computer. When you select the desired message, the client program downloads the entire message. In this case, you can work on-line and off-line. Read messages are not deleted, you can carry out the desired operations with them in the future.
Pros and cons of IMAP and POP3
Which protocol should you choose? It all depends on the specifics of the job and needs.
In addition to the fact that messages are saved on the server without deletion, the advantages of IMAP include:
- Possibility of access to the mailbox from several clients;
- Support for simultaneous access of multiple clients;
- Support for multiple boxes;
- The ability to create new folders that can be accessed by other users;
- Ability to mark emails as read, important and others;
- Server search support;
- The ability to work in on-line mode.
The only drawback in this case is that the user spends more time downloading letters from a central computer.
Everyone knows how to work with e-mail. We open the browser, look for the required resource, log in and read the received e-mail. The pop3 and imap mail protocols allow you to work with mail without a browser, using client programs, as if the files are located directly on the local computer.
Definition
POP3- Internet application protocol, providing access to the mail server via TCP / IP and using port 110.
IMAP- Internet application protocol, providing access to the mail server via TCP and using port 143.
Comparison
The difference between POP3 and IMAP is applied. Both protocols perform identical tasks, only POP3 allows you to download all files at once (these files store the correspondence), and IMAP - first a list of files and then selectively - themselves. This is the main difference between the protocols, and the newer IMAP was created precisely to implement this difference: clients were not satisfied with the need to parse mail locally, while on the server, after downloading, files were deleted. On IMAP servers, the user controls his own messages.
Pop3 clients connect to the network only to download files to the local computer, disconnect after the operation is completed, and further work of the programs takes place in offline mode. IMAP clients can work offline, but online provides more options for them: for example, managing messages on the server. As a result, offline access requires fewer resources and is faster, while online access is more dependent on network conditions and exhibits relatively long response times.
POP3 assumes mono-user access to the mailbox, IMAP allows multiple clients to connect to it, while the work of any of them is not limited, and everyone sees the changes made by others. IMAP also allows the user to see the status of messages, move them, create folders and delete them as if they were dealing with a local copy. Messages are not automatically deleted from the server.
Another important difference between IMAP and POP3 is the ability to extend the IMAP protocol and ultimately obtain fine-tuning, for example, client access rights to the server. Despite the fact that POP3, due to its longevity, is more widespread and easier to configure, IMAP seems to be more convenient for solving many tasks, for example, corporate.
Conclusions site
- IMAP uses port 143, POP3 uses port 110.
- IMAP works both online and offline, POP3 only offline.
- IMAP allows you to manage messages directly on the server, POP3 downloads files to the user's local computer.
- POP3 provides faster access
- In IMAP, you can configure split access rights.
