Re: I use thunderbird, and don't want to see it go
"Seamonkey is still going strong for the truly nostalgic."
When re-homing Thunderbird with the Document Foundation was looked at some months ago one of the issues raised was the need to re-skin it to fit in with LibreOffice. In its Seamonkey guise the mail client wouldn't be a problem. Ironically it seems that LibreOffice (and OpenOffice?) had a good deal of Seamonkey code buried in it until fairly recently in order to have access to the address-book.
As a user of both Seamonkey and LibreOffice my preferred choice would be to see the Document Foundation look after the whole shooting match giving the option of anything between a free-standing email client and a complete package.