Correctly Using Postfix Virtual Aliases for Email Routing

Correctly Using Postfix Virtual Aliases Email Routing

Email routing is a crucial aspect of email server configuration. One popular open-source solution for email routing is Postfix. Postfix allows for the use of virtual aliases, which enable the administrator to route incoming email to different local or remote mailboxes based on the email address. This article will provide a detailed explanation of how to correctly use Postfix virtual aliases email routing.

Postfix Virtual Aliases

Virtual aliases are a way to route incoming email to different destinations based on the email address. This is particularly useful in a scenario where you want to handle email for multiple domains on a single server. With virtual aliases, you can specify a mapping of email addresses to different local or remote mailboxes. This mapping is defined in the /etc/postfix/virtual file.

# Example virtual file
# Map [email protected] to username1
[email protected] username1

In the above example, any email sent to [email protected] will be delivered to the local mailbox of username1.

Email Routing

Once the virtual aliases have been defined, the next step is to configure Postfix to use these aliases for email routing. This is done by adding the following line to the /etc/postfix/main.cf file:

virtual_alias_maps = hash:/etc/postfix/virtual

After making this change, you will need to run the postmap command to build the database for the virtual aliases:

# Run postmap to build the database
$ sudo postmap /etc/postfix/virtual

Finally, you will need to reload the Postfix configuration for the changes to take effect:

# Reload the Postfix configuration
$ sudo systemctl reload postfix

Regardless of User Specified

One important aspect of virtual aliases email routing is that the email should always arrive in the inbox, regardless of the user specified in the email address. This is achieved by using the local_recipient_maps parameter in the /etc/postfix/main.cf file:

# Map local recipients to local mailboxes
local_recipient_maps = unix:passwd.byname $alias_maps

With this setting, Postfix will use the passwd.byname file and the alias_maps (which includes the virtual aliases) to determine the local mailbox for a given recipient. This ensures that the email is always delivered to the correct mailbox, regardless of the user specified in the email address.

• Virtual aliases allow for the routing of incoming email to different local or remote mailboxes based on the email address
• The virtual aliases are defined in the /etc/postfix/virtual file
• Postfix is configured to use the virtual aliases for email routing by adding virtual_alias_maps = hash:/etc/postfix/virtual to the /etc/postfix/main.cf file
• The postmap command is used to build the database for the virtual aliases
• The local_recipient_maps parameter is used to ensure that the email is always delivered to the correct mailbox, regardless of the user specified in the email address

References

• Postfix Virtual Aliases Readme
• Postfix local(5) man page