2.24.3.7. Error 553 5.7.1 Sender address rejected: not owned by user

Error "Sender address rejected: not owned by user"Which appears when sending a letter indicates an attempt to send a letter using someone else's or another mailbox. There are two situations in which this error can occur:

• In case the letter is sent with the indication of another mailbox, but within the same domain.
• If the letter is sent with the indication of a different mailbox using a different domain.

Note: the error will indicate the mailbox in which the authorization was performed, and the mailbox that will be indicated as the sender:

(5.7.1 <admin@example.com>: Sender address rejected: not owned by user mail@example.com)

• admin@example.com - the mailbox in which the authorization was made.
• mail@example.com - the mailbox specified as the sender.

If, when sending a letter, authorization was performed within the mailbox admin@example.combut when sent as sender (title From:) the mailbox is specified mail@example.com, but the error occurs – this means that the parameter “Allow sending emails from other users within your domain name.". To fix the problem, you should either not use specifying a different mailbox, or enable the parameter allowing sending with indication of another mailbox.

If, when sending a letter, authorization was performed within the mailbox admin@example.combut when sent as sender (title From:) the mailbox is 'admin@domain.com' (the difference between them is in the domain name), then you need to specify the correct mailbox within the domain used for the mailbox to which you are connecting. Sending with a completely different mail is not possible.