Sender and receiver model
When a mailbox is created, a user is allowed to send mail from and receive mail for his own mailbox address.
Mailbox email@example.com is created. example.org is a primary domain. Note: a mailbox cannot be created in an alias domain. firstname.lastname@example.org is only known as email@example.com. firstname.lastname@example.org is allowed to send as email@example.com.
We can add an alias domain for example.org:
Alias domain alias.com is added and assigned to primary domain example.org. firstname.lastname@example.org is now known as email@example.com and firstname.lastname@example.org. email@example.com is now allowed to send as firstname.lastname@example.org and email@example.com.
We can add aliases for a mailbox to receive mail for and to send from this new address.
It is important to know, that you are not able to receive mail for
firstname.lastname@example.org. You would need to create this particular alias.
email@example.com is assigned the alias firstname.lastname@example.org email@example.com is now known as firstname.lastname@example.org, email@example.com, firstname.lastname@example.org email@example.com is NOT known as firstname.lastname@example.org.
Administrators and domain administrators can edit mailboxes to allow specific users to send as other mailbox users ("delegate" them).
You can choose between mailbox users or completely disable the sender check for domains.
SOGo "mail from" addresses¶
Mailbox users can, obviously, select their own mailbox address, as well as all alias addresses and aliases that exist through alias domains.
If you want to select another existing mailbox user as your "mail from" address, this user has to delegate you access through SOGo (see SOGo documentation). Moreover a mailcow (domain) administrator needs to grant you access as described above.