Why does this happen?

[Cutsizzle]

When I try to email my users, it'll email about 200 of them and it says "Emailing ok" but then it'll stop on a random member and won't finish the process.

[Lynne]

Check your error_logs (if you don't know where they are, ask your host) and see if anything is there. If not, ask your host if they limit your emails per batch/hour/time period.