You can define how many mails Mailster send in a certain period so you can respect your providers limits
Use this form to calculate your settings:
I can send mails within hours
My cron interval is minutes
Your limits are
Send max 34 emails at once and max 10000 within 24 hours
A campaign with subscribers will take approx. 02:36 h to get finished
Sending more than 200 at once can cause server timeouts!
You should decrease the cron interval!