my hosts allows 1500/hour, i've set 210/batch, is it ok?

Use mailqueue system - Yes/Yes with locking? i kept yes as of now..
I've 40,000+ users..

anything else i need to edit in settings or default is fine?

well you can manually adjust how often the queue sends and how many it sends per batch.
So if you have 1500...say you need to save like 250/hr for other emails your board sends out, so this means you can send 1250/hr without going over your limit.
If you wanted large batches you could send only like 250 every 15min or do small batches of 20 every 3min. Just as an example...I didn't actually figure the math out on those :p

Does this work with Admincp -> Users -> Send email to users ?

As it says ;

Hi Paul,

Will test this out... Thanks. Would be great if in the future you also could add feature that 1x time per week and email is send to all users.. or per maybe 2x weeks, where in the email, we can add recent posts added, most popular topics of last month etc etc.. This way we can keep the users updated on all items :).

Maybe also... the ability to add holidays into the system and send out pre arranged emails like on Christmas to the users with a particular text that has been set before. :)

Thanks.

Paul,
Is it a "set it and forget it" setting?

I mean, Is there anything I need to do after I choose "Users > Send Email To users", write the subject, email body and click on Submit?

Does this work as well for forum subscription notifications?

If they use the vb e-mail queue then yes.

i edited the functions file exactly as stated (not the functions exec_mail_queue();, just exec_mail_queue();) to
// exec_mail_queue(); // Paul M - Cron Mail Queue Hack //

and I get the functions.php syntax error. The line exec_mail_queue is in there twice, once with functions before, once without. I tried changing both, and tried changing just the one with function before it, and tried just with the one that doesn't have function before it. All combos cause the syntax error. When I change the line back, the error goes away.

vbulletin 4.1.1

any ideas Paul? did something in the latest version "break" your modification?

Nothing has changed in 4.1.1, so you must be making some kind of mistake, or somehow corrupting your file.

JFYI, the line is near the end of the file (i.e. not the function definition).