Postfix How virtual domains work

Understanding how a virtual domain works is important to understanding the establishment of our virtual messaging system. There are two types of domains in Postfix.

Local domain: All mydestination point domains are postfix as local. Messages in the local domain are sent to users who appear in the passwd file and are stored in the/var/mail directory.
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Virtual domains: Postfix can also send letters for virtual domains in addition to the local domain. Unlike local postfix, we can manipulate virtual domains in a flexible way. His advantage is that we do not need to establish a system account in the passwd file for each mail account. This provides an easy way for our messaging system to control thousands of mail accounts. We use the mappings discussed earlier to control mail account information. You can use MySQL, PostgreSQL or LDAP for mail account management. In the system we install, use MySQL to manage the mail account of the virtual domain

Postfix uses two different classifications to control virtual domains, and needs to understand how they work.

Virtual alias domain: He is used to forward an alias message from an email address to another email address. This domain can be used as a receiving mailbox and stored on your hard drive. The virtual alias domain is not required in the system you are building. We can use the Virtual Alias mapping table to replace the virtual alias domain, even those that do not appear in the virtual alias domain. The Virtual Alias mapping table is a normal redirect mapping table. The function of this table is (the virtual_alias_maps is a general-purpose redirection mapping this works for modifiable that passes your system including local domains.)

Virtual mailbox domains: ' Postfix use these domains to receive mail for users in a domain and to save messages to a mailbox on your hard disk. This is a parameter that tells Postfix to receive messages from the domain and store them in each user's mailbox. Postfix determines the location of the mailbox on your hard disk using the mapping of the Virtual alias mapping table. Keep in mind that you can still forward a message to another mailbox or to an external e-mail address using the mapping of the Virtual alias mapping table. So not every domain user has to have an actual mailbox, you can just forward the mail to another place.

It is important to understand that a domain is necessarily a virtual alias domain, a virtual mailbox domain, or one of the local domains. If you set a domain to be a virtual alias domain you will not be able to receive mail for this domain on your server. Instead, you can use the Virtual Alias mapping table to Forward?action=attachfile&do=get&target=alias email for both types of domain. So virtual mailbox domains can be used more flexibly.

A domain is either virtual or local. You can't have one domain with two features at the same time. So if you want your default domain to be virtual, then you have to delete it in the mydestination definition. Just set Mydestination=localhost or write nothing. Addresses such as Root@localhost will be sent to the local root user.