Mac Mail / send from WorkMail Alias

Hi there,

This could be an Apple problem, but it could also be an AWS problem. I have an alias set up on my WorkMail email address. If I use WorkMail's webmail, I can send from that alias by manually typing the alias address into the From field. Cumbersome, but it works.

In Mac Mail, I have added the alias as an additional email address on the relevant account. I'm sure this previously also worked fine. "Previously", however, being a long a time ago. It hasn't worked for (possibly) years. I can select the alias when sending, and Mac Mail happily thinks it has sent from that alias. However, looking at the sent items in webmail, the sender address is my primary one, not the alias. And, of course, looking at the email received, it's from the primary address.

I've tried the only basic measure I could think of, to delete the additional email alias in Mac Mail and re-add it, to no avail.

Do you think this issue is WorkMail, or Mac Mail? Or a configuration issue somewhere? Does anyone else have the same issue?

Thanks,

Graham