On this page you will find everything you need to know about POP and IMAP protocols, understand and know pros and cons, server connection ports, email account connection security (encryption) and authentication methods.
The POP protocol
This protocol is designed for processing emails in "connected-only" mode: all emails are downloaded to the user's computer by the email software and can be deleted from the server. A connection is then only required to check for new messages.
With the POP protocol, your email client will download messages at regular intervals and save them on the device you are using . By default, messages are downloaded, saved on the device, and deleted from the server after a defined period.
This functionality allows quick access to data (for searching or sorting your messages).
It is possible to configure this type of POP account to:
- automatically delete emails from the server that have already been read (downloaded to your device). You then don't have to worry about the disk space used on your hosting.
- Keep a copy of messages on the server, either for a given period or indefinitely.
This setting has the disadvantage of not allowing direct visibility into the data stored on the hosting, but allows you to maintain access to your recent emails from another device (mobile phone, laptop, tablet, etc.).
The advantages of POP | The disadvantages of POP |
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When you retrieve mail from a POP account, most email clients automatically delete messages from the server by default after a set period of time.
To retrieve your email from another computer/device, or if the mailbox is accessed by multiple people, you can configure your email clients to keep a copy of each message on the server until your other email clients have downloaded it. Simply adjust the message retention period on the server accordingly before deletion.
Note: It is also possible to adjust this setting to reduce the size of your hosting by reducing the storage period or disabling server-side email storage.
Refer to the support for the email client you are using for help setting up your software, and in particular to learn how to change email storage settings on a POP account, in order to delete or keep a copy of your messages on the server.
The IMAP protocol
This protocol is recommended for use on multiple devices (synchronization).
With this protocol, messages are not deleted during retrieval, but all changes made to your account (moving, marking, deleting) are also applied on the server side.
For these reasons, the IMAP protocol is very well suited to mobile uses (successive connections from work, home or while traveling...) as well as to the processing of a professional mailbox by several people, because changes made from one account are visible on all the others.
It also allows you to benefit from backups made on the server, since the data remains stored there. Therefore, it is possible to restore the data in the event of a failure on your workstation.
The advantages of IMAP | The disadvantages of IMAP |
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Server ports
- IMAP:
• Incoming server: 143 without security or 993 with SSL/TLS
• Outgoing server (SMTP): 25 or 8025 (not valid on all SMTP servers) without security or 465 with SSL/TLS or 587 with STARTTLS
- POP:
• Incoming server (POP3): 110 without security or 995 with SSL/TLS
• Outgoing server (SMTP): 25 or 8025 (not valid on all SMTP servers) without security or 465 with SSL/TLS or 587 STARTTLS
| Kind | Server/Host Name | User name | Port | Connection security | Authentication method |
| POP | … | e-mail address | 995 | SSL/TLS | Normal password |
| IMAP | … | e-mail address | 993 | SSL/TLS | Normal password |
| SMTP | … | e-mail address | 587 | STARTTLS | Encrypted password |
| SMTP | … | e-mail address | 465 | SSL/TLS | Normal password |
Port 465 was implemented for email clients that did not support encrypted passwords. On port 465, it doesn't matter whether the password itself is encrypted or not; it's the session that is encrypted , so the password's integrity is irrelevant.
On port 587 , it is the password that is encrypted and therefore it is the right option to choose without security on the connection.