[Exim] Bug in quota calculation for maildir delivery

Hello,

I think there is a bug in 3.12 src/transports/appendfile.c around line
2241. With maildir, the message is first delivered to tmp, then the
new size is calculated. Unfortunately, the code compares the new size,
which includes tmp, _plus the message size_ with the quota. As such,
you can fill up your mailbox with small messages, but you can not get
a mail larger than half your quota.

Michael