thanks for taking the time to report this.
You ran into an issue that should have been fixed before. So I am marking this bug report as a duplicate of the former bug report and re-open it.
As a workaround you could try to reset the gesettings for Mail:
1) close Mail
2) $ dconf reset -f /org/pantheon/mail/
This problem is quite hard to reproduce.
Could you describe what you did before Mail kept growing its size?
Dear Brendan,
thanks for taking the time to report this.
You ran into an issue that should have been fixed before. So I am marking this bug report as a duplicate of the former bug report and re-open it.
As a workaround you could try to reset the gesettings for Mail:
1) close Mail
2) $ dconf reset -f /org/pantheon/mail/
This problem is quite hard to reproduce.
Could you describe what you did before Mail kept growing its size?