Hi all,

Is there a way to limit users to use secondary SMTP addresses to mail external?

For example:

John Smith has manager@contoso.com as his primary SMTP and j.smith@contoso.com as secondary SMTP.

John may only mail external with his primary SMTP manager@contoso.com

I can only block users currently, cause if I add secondary SMTP tobe blocked, it will recognize the User like it does with the Check names button...

thanks in advance

There is no way for users to send email as an additional alias address using the native clients (Outlook, OWA and ActiveSync). The only way a user could send using an alias would be via SMTP. In that case doing a transport rule check on the from field would block the traffic.

Simon.

Hi,

We can try this transport rule for users.

If there are many users or users with not just two email addresses, it will be a huge project.

Best Regards.

I gave it a try and it worked!

I had a rule in place but got stuck by starting to apply it on my users as Senders from inside the org. This would result in only recognition of user names in exchange and not SMTP aliases. So it would block the user object and not the secondary SMTP

Thanks!

• Edited by P.Hilhorst 12 hours 44 minutes ago