I have been using Gmail for a long time and one of the features that I enjoyed has been the ability to retrieve mail from other accounts automatically, which makes consolidating your various email accounts a cinch. Otherwise, you have to set up many different accounts on your mail client, if you have several accounts to keep on top of, like me.
Suddenly, during December last year, I noticed that this feature was not working anymore and I was not sure what was causing it. First I checked to make sure that my mail server had not caused the problem. After spending a bit of time looking through the server authentication log, I did not see any problems with the user credentials. A few head scratches later, I found the culprit in Gmail itself.
Apparently, there was a change in Gmail settings in the way it treats self-signed certificates. The accounts that I checked through Gmail are hosted by a mail server that I control, using self-signed certificates. It was fine for a while, but now Gmail thinks that no SSL security is better than using a self-signed certificate.
Considering how many CAs have been compromised lately, I feel that making people drop SSL encryption because their certificate was not signed by a registered CA is a little on the strange side.