The status of null-sender spam from outlook.com
Recently, David left a comment on my last entry on null sender spam from outlook.com noting that his site had seen a stop of null sender spam from Outlook at the end of December. This made me curious about what we're seeing (and David asked, too), so I've now gone looking.
The short version is that clear null sender spam from outlook.com appears to have stopped at the end of last year (and I mean literally the end of last year, as we have entries from December 31st). We're still getting some amount of email from outlook.com with null sender addresses, but our anti-spam system now scores all of it very low. I can't be sure that this isn't spam, but it's certainly entirely possible that it's real bounces. We continue to get spam from outlook.com in general; at the moment, our 2016 figure is that about 4% of email from outlook.com scores high enough to be considered spam. In December the logs say it came out to be about 11.5% spam, so we clearly saw a significant drop here.
David also reported a lack of general spam from outlook.com. Unfortunately we don't see that. Outlook.com has been consistently sending us some amount of spam (as scored by our systems). In addition, several outlook.com hosts are currently on the SBL; out of microsoft's listings, I can spot more than five listings. However the SBL seems to be doing something odd here, in that they're listing .0 addresses in the /24 instead of the actual IP address they list in the SBL listings. The net effect is that nominal SBL listings won't actually block anything, which kind of irritates me.
(Eg, SBL273948 says 'Spam source @18.104.22.168' but is for 22.214.171.124/32.)
My overall view is that outlook.com continues to have a spam problem, but they have apparently managed to block or otherwise stop one source of their spam. This is progress; it is just not enough progress. Having roughly one in twenty email messages that we receive from you being spam is not a good ratio. For scale, over the same period in 2016, only 0.2% of the email received from Google was scored as spam.
(This includes both GMail email and email from some other things at Google that send out email, since as far as I know you can't tell the email servers apart, assuming there even is different infrastructure for the various different email systems.)