People who run their own mail servers are increasingly finding that the mail they send to Gmail users is being rejected, because the company's anti-spam algorithm treats small, independently managed mail-servers as high-risk mail sources.
And since Gmail users never receive the blocked messages, it can be impossible to convey to them that they're missing some messages.
This happened to me last month and Ken Snider, our awesome sysadmin, was somehow able to fix it, but Google doesn't make it easy.
Email is one of the last federated systems in widespread use on the internet. That fact is why newsletters are on the rise: using email to convey your message means "you don't have to fight an algorithm to reach your audience." But now you do.
I'm sure there is no malicious intent behind this and that there are some very smart people working on spam prevention at Google. However for a metric driven company where a majority of messages are only passed with-in the walled garden, I can see how there's little motivation to work well with mail coming from outside. If all training data is people marking external mail as spam and there's much less data about false positives, I guess it's easy to arrive to a prior that all external mail is spam even with best intentions.
Google is eating our mail [Tomaž Šolc/Avian's Blog]
(via Webshit Weekly)