We recently changed web site hosts. They now also host our email. When we send to some address's it comes back as, for example:
Unknown user: firstname.lastname@example.org"
This is a known good address that worked prior to changing email servers. I can't even go to the web login and email to this address without outlook. HOWEVER!.... If I use Mozilla Thunderbird on the same pc it emails to this address just fine. The first thought is just use Thunderbird...however...I have 125 users that use Outlook that don't want to change. Any thoughts?
PS: please don't flood my email just to see if it works