We don't have the limit, but one of my private hosts does impose that limit. But the newsletter that told me about it also mentioned to contact them if that limit is in your way.

Your provider probably couldn't care less if you are a mass mailer that is sending out genuine messages to people who want them.

But by imposing that limit, they secure themself against bad/hacked scripts that send out the spam.

[Linked Image from siemons.org]