365 mail flow rule alias returns text messag to sender

Question

Hello,
Recently I had to change the email names in my organization.
So email: abc@mathieu.company .com was renamed to dave@mathieu.company .com and abc@mathieu.company .com was added as an Alias.
I'd like to notify any external sender who is still sending to abc@mathieu.company .com that the email has been changed by returning a pre defined message.
I'd rather not use AutoReply.
Is there a way to make a mail flow rule or any other solution at the server level so that end user 'dave@mathieu.company .com'
is not bothered and is not aware of?

Thanks, Michael

Answer 1

There is no real good server side solution for this. You can't do this with a transport rule.
An auto responder in Outlook is the only real built-in solution. (There may be 3rd party solutions that cost money

https://www.emailstopwatch.com/how-to-setup-an-autoresponder-in-microsoft-outlook/