[MlMt] Possible memory issue in latest test release

[Benny Kjær Nielsen]

Hi MailMate users,

I'm trying to make the current test release ready for a public release,
but I have a user reporting a possibly new memory usage issue. MailMate
has always been memory greedy, but this user has seen the memory usage
increase to a level that makes MailMate unusable within a few hours (up
to 60GB). I've fixed a memory allocation issue with the new mailbox
list, but this does not appear to have fully fixed the problem.

Anyone seeing a similar issue with the latest test release is welcome to
contact me via “Help ▸ Send Feedback”. (I cannot yet reproduce the
issue myself.)

Hold down ⌥ when clicking “Check Now” in the Software Update
preferences pane to get the release (r5543). I do recommend using this
release, especially on Mojave, but keep an eye out for the issue
described above.