I have a droplet running a mail server with dovecot, postfix and mysql.

On this droplet I have multiple domains: example1.com, example2.com, and so on.

Postfix uses example1.com as the hostname so any email account name@example1.com can authenticate to this server using a mail client and the SMTP/IMAP hostname: mail.example1.com

The problem is that user@example2.com can't authenticate with the server using mail.example2.com.

What changes (probably DNS records) are required in order to allow each user to access the mailbox using the same domain name as the email account.

For example (using any mail client Outlook/Thunderbird/etc.):

• user1@example1.com uses SMTP/IMAP mail.example1.com
• user2@example2.com should use mail.example2.com

Any thoughts?