Testing Exchange Online via manual SMTP submission
For some reason it seems I’m developing an Exchange theme in recent posts, but I came across an issue with this recently so decided to write it up for my own future reference. You had me at EHLO This was the name of the Exchange Team blog back in the day and it remains the high watermark of wit for an email nerd. Back when I was an Exchange server admin I could compose a message via telnet almost as quickly as I could do it in a mail client; I knew all of the commands and their sequence like the back of my hand as it was always easier to get the server’s response directly rather than trawl through logs when figuring out a problem....