Thanks anyway Harv,out of interest are there more reliable apps other than the deadly duo that I use?
Thunderbird is my favourite email application, but I keep Apple's Mail on hand, though I never use it, in case Thunderbird takes a dive, and in case Mail's absence screws up any Apple software updates, and in case a software update improves it. I consider it a full-size spare in the trunk.
If Mail is in the computer but never used, it can cause no more trouble than if it's trashed. And it would be handy to have around when trying to figure out the server settings for any new email app.