English
For more information on installing packages with DNF, see xref:package-management/DNF.adoc#sec-Installing[Installing Packages].
When using a `POP` server, email messages are downloaded by email client applications. By default, most `POP` email clients are automatically configured to delete the message on the email server after it has been successfully transferred, however this setting usually can be changed.
`POP` is fully compatible with important Internet messaging standards, such as _Multipurpose Internet Mail Extensions_ (_MIME_), which allow for email attachments.
`POP` works best for users who have one system on which to read email. It also works well for users who do not have a persistent connection to the Internet or the network containing the mail server. Unfortunately for those with slow network connections, `POP` requires client programs upon authentication to download the entire content of each message. This can take a long time if any messages have large attachments.
The most current version of the standard `POP` protocol is `POP3`.
There are, however, a variety of lesser-used `POP` protocol variants:
*APOP* — `POP3` with `MD5` authentication. An encoded hash of the user's password is sent from the email client to the server rather than sending an unencrypted password.
*KPOP* — `POP3` with Kerberos authentication.
*RPOP* — `POP3` with `RPOP` authentication. This uses a per-user ID, similar to a password, to authenticate POP requests. However, this ID is not encrypted, so `RPOP` is no more secure than standard `POP`.
For added security, it is possible to use _Secure Socket Layer_ (_SSL_) encryption for client authentication and data transfer sessions. This can be enabled by using the [command]#pop3s# service, or by using the [command]#stunnel# application. For more information on securing email communication, see xref:Mail_Servers.adoc#s2-email-security[Securing Communication].
IMAP
indexterm:[email,protocols,IMAP] The default `IMAP` server under {MAJOROS} is [application]*Dovecot* and is provided by the [package]*dovecot* package. See xref:Mail_Servers.adoc#s3-email-protocols-pop[POP] for information on how to install [application]*Dovecot*.
When using an `IMAP` mail server, email messages remain on the server where users can read or delete them. `IMAP` also allows client applications to create, rename, or delete mail directories on the server to organize and store email.
`IMAP` is particularly useful for users who access their email using multiple machines. The protocol is also convenient for users connecting to the mail server via a slow connection, because only the email header information is downloaded for messages until opened, saving bandwidth. The user also has the ability to delete messages without viewing or downloading them.
For convenience, `IMAP` client applications are capable of caching copies of messages locally, so the user can browse previously read messages when not directly connected to the `IMAP` server.
`IMAP`, like `POP`, is fully compatible with important Internet messaging standards, such as MIME, which allow for email attachments.
For added security, it is possible to use `SSL` encryption for client authentication and data transfer sessions. This can be enabled by using the [command]#imaps# service, or by using the [command]#stunnel# program. For more information on securing email communication, see xref:Mail_Servers.adoc#s2-email-security[Securing Communication].
Other free, as well as commercial, IMAP clients and servers are available, many of which extend the IMAP protocol and provide additional functionality.
Dovecot
indexterm:[email,mail server,Dovecot] The [command]#imap-login# and [command]#pop3-login# processes which implement the `IMAP` and `POP3` protocols are spawned by the master `dovecot` daemon included in the [package]*dovecot* package. The use of `IMAP` and `POP` is configured through the `/etc/dovecot/dovecot.conf` configuration file; by default [command]#dovecot# runs `IMAP` and `POP3` together with their secure versions using `SSL`. To configure [command]#dovecot# to use `POP`, complete the following steps: