Bounce-Mail Error: 553 5.7.1 xxxxxxx@xxxxx.xxx: Sender address rejected: not owned by user xxxxx@xxxxx.xxx

This error can occur immediately when sending a message. Often you receive it directly in your mail client and not in an error e-mail (bounce message). It means that the first e-mail address specified as the sender of the message in the error message (xxxxxx@xxxxx.xxx) cannot be used for sending by means of the SMTP outgoing server of the mailbox specified as the second one (yyyyy@yyyyyy.yyy).

The error occurs if you have specified a different e-mail address as the sender of an e-mail message than the address of the mailbox through which you are sending this message.

For example: you have set up a mailbox for the e-mail address ‘address@mydomain.com’, use the login information for this mailbox to log into the Mailix mail server for sending, but use the e-mail address ‘other@mydomain.com’ as the sender of this message.

By default, for security reasons, we only allow sending with the e-mail address of a mailbox or with any secondary address (alias) of that mailbox as the sender address of the message.

If the desired different sender address is in your own domain, you can simply set up the corresponding e-mail address as an alias address (secondary address) for your mailbox in the Mailix UI. Afterwards you can also send messages under this email address (despite logging in with the main address) as the sender.

Furthermore, in the Mailix UI you can setup for each mailbox that a certain or all configured e-mail addresses of your domain can be used as senders by any mailbox user.

If you have purchased an optional alias domain from us, you can also set this up across all domain names assigned to you.

What is not possible, however, is you cannot setup an email address of a domain that is not set up for you at Mmailix or not owned by you as the sender of any message.