In DNS, I have
service.example.com. CNAME box.example.com. When sending email automatically to about 10,000 adresses (no worries, nothing sinister), I set envelope-from to
firstname.lastname@example.org. Of the bounces that come back, about 70% have envelope-to set to
email@example.com (which is what I would expect), but about 30% have envelope-to to
What is going on here? Do some MTAs change envelope-to when they discover a CNAME? Which MTAs?
Is it a good idea to use an A record instead of a CNAME for