I am working in a small programming company and administrated the mail-servers for quite a while.
Now we moved our web site and the MTA to a company that we considered to be more professional. But I realized, that none of my emails arrived my colleagues — sometimes I got an error mail, sometimes not. The error indictated, that my SMTP server was faulty and that it need to be fixed.
Having this problem for the first time in many years, I contacted the others company's admin for some explanations:
He told me, that I send the mails with SMTP-server, that has another server name than my email address' domain name. I answered that that is absolutely legal, as I don't have SMTP-Server declared for all my accounts, but all my SMTP-server are authenticated servers, so that should be absolutely ok.
The admin responded, that this is not true, that it is absolutely common to block email, if they are send via another SMTP-server to prevent spam.
Again me: that is not common, as in many networks you have to use their SMTP-server, i.e. I know several university networks and in several countries people, citizen and foreigners, are forced by the internet providers to use special servers,...
The admin told me, that he can't understand my examples and that in my mentioned cases people are always forced to either use other mail addresses or web mailers. Additionally he wrote a mail to the person he thought of as my boss (actually we are partners), that I am telling terrible lies and would propagate securities flaws and should be fired.
Now we started to search for another company to run our servers, but I really wonder, who is right?
Should a Mailserver reject a mail, if it is send via another — but authenticated — SMTP server, or would that lead to many problems?