Murphy's law and it's corollaries dictate that not only will things that can go wrong will go wrong, but they will do so at the least possible convenient time. Thus it was that at the end of April as I was getting ready to transition to a few months of full-time travel Apple's Mail app decided to head south. The main symptom was an incredible use of memory. I could launch Mail and a short time later not only would all 8GB of RAM in my machine be swallowed up but it would be using 20GB more on disk for swap space. All and all a totally unusable situation.
Since I now spend precious little time at home I just switched to using MailPlane and called it good. MailPlane uses the native Google Mail interface which has a major advantage in the form of the Send and Archive button. With the flood of hundreds to thousands of emails a day in my inbox this is a powerful tool. However it lacks other processing rules like the priceless Mail Act-On.
A brief deviation here while I rant for a second about how inexplicable it is Google has never come up with the concept of rules applied once email has arrived. In most cases I need to see the message in my inbox and make decisions about it and then I want to process it. Mail Act-On does this beautifully and even uses Apple Mail's rules to full advantage to simplify having the same keystrokes affect multiple accounts and take the right action on an account-by-account basis. But this Google Mail gripe aside back to the story.
Wrestling with the issue I'd tried suggestions of rebuilding, reindexing and recreating accounts left and right. As I have a couple of accounts with north of 5GB of mail in each it's no small task to try these things but they were all tried and while some seemed to work momentarily none lasted. This weekend I did some cleanup on the desktop machine and launched mail for the first time. A notice came up that the plugins like MailActOn and MailTags had been disabled. After a few hours away from the computer I returned to find the machine had not used all available memory and didn't have fans running at tsunami speed.
I've begun adding back the plug-ins and we'll see how the process goes. The critical one, Mail Act-On, seems to be fine. I've never gotten around to being a heavy MailTags user so if it's the culprit it won't be much of a problem to disable it. Indeed it could just be that all of the updated versions will come together to make things much better.
Another nice benefit is Safari now seems to be doing a better job of handling pop-ups that I specially open in windows now open in windows instead of another tab. This is great for IMCE for example. Here again it's more than possible that something I did back when was causing the problem but the previous behavior would open a new tab which was fine. However when that tab was closed it returned you to the rightmost tab, not the tab that opened the new tab.