I noticed that sometimes, like when my server is doing something really hard drive intensive, then mailings will crap out mid-stream.
Having to babysit it just to hit the "resume" button gets to be very annoying.
So I added this little hack...so via javascript the button automatically pushes itself.
Around line 1729 on admin.php, I appended the echo statement with the following code:
<script language=\"Javascript\">setTimeout(\"hopto('./domail.php?resume=1&batid=$batid&list=$list')\",90000)</script>
Then, around line 124 of the domail.php script I also added this:
<script language=\"Javascript\">setTimeout(\"hopto('./domail.php?resume=1&batid=$batid&list=$list')\",60000)</script>
Now, I no longer have to babysit mailings to ensure they finish, because they'll now autoresume.