Sender is not authorized by default message

Question

Hi guys, I get the following message "Sender is not authorized by default to use ‘mail-service@MyCompany.com’ …" when I put ‘mail-service@MyCompany.com’ into the Sender filed and the message ends in a Spam folder for some of my clients (not all of them). Any advice on the subject? (MyCompany would be something real, of course). It's probably some configuration but I want to check here first. The message is sent using Rebex.Net.Smtp.Send.

Answer 1

Hi Maxim,

the error message suggests that you are trying to send the email as a different sender than the one which owns the mailbox (e.g. 'mail-service@MyCompany.com'). Could you please check on that?

If you are sure that you should really be able to send through the 'mail-service' account with a different sender, then it is a matter of configuring the SMTP server in a right way to allow this as it depends on the SMTP server whether it will accept message with a 'different' sender or not.