Re:Google Apps stops accepting free sign-ups
by vacri on Friday December 07, 2012 @02:56AM
(#4885985)
Hrm. Perhaps it was a certificate issue with SSL which the guy uses on his mailserver? I'm really not up to speed with configuring much beyond msmtp.
In any case, from a decade of listening to the random things he's had to deal with, I certainly have to agree with your final comment.
Re:Google Apps stops accepting free sign-ups
by jrockway on Friday December 07, 2012 @02:28PM
(#4888761)
SSL'd SMTP is a non-standard extension that nobody uses. (In fact, the port assignment for it was revoked in 1999!) TLS on port 25 is how you do secure email (mostly so you can advertise AUTH PLAIN safely.)
I think there are probably some MTAs that will STARTTLS for normal SMTP connections, but again, I've never heard of anyone using SSL/TLS as a spam-filtering criterion. (I might look through my old logs to see if anyone other than me ever issued STARTTLS on my mail server. But I'm guessing the number was near zero.)
There are no internet authorities that control mail delivery, either, BTW. Many sites use heuristics to control mail acceptance, however, including third-party whitelists and blacklists. It can suck if you get on a blacklist, but experienced mail administrators only use whitelists and blacklists as one of many metrics regarding mail spamminess. Indicators of good mail like "most of the words in this message are non-spam words" often provide an order of magnitude more ham points than blacklists contribute spam points, so important messages will probably not be dropped even if you're on a blacklist. Of course, many sites have less clever schemes because there is a lot of spam and not a lot of sysadmin time to waste tweaking spam filtering rules.
Mail is hard.