Yesterday I discovered that about half of all emails sent using my ISP’s SMTP server are rejected by my recipient’s mail servers. The reason: since a long while my personal ISP, Online (former Orange, even more former Wanadoo) is blacklisted for spam reasons.
As I understand when surfing the Internet for this problem, many users suffer from the same problem. I decided it was time to do something myself, as I cannot rely on the SMTP server anymore. Therefore I looked for a reliable SMTP relay server (paid, to prevent myself to overcome the same problem again). That particular relay server must support the Exchange Server’s smart host on an alternative SMTP port, since Online has closed port 25.
Since a couple of hours I use the mail relay service of DNSexit for just a few bucks per year. All functions wonderful, my mail arrives again (not unimportant). I also tried using SMTP2GO, but unfortunately they do not support an Exchange Server smart host.