how can i use the mass mail option

[gbox master]

i recently went from phpbb 2 vBulletin
now i have a problem when i want to send members a mail
the hosting allows a certain amount of mail per batch
so i have to set it to aprox.300 now i find that i need to push a button every 300 mails
the first time when i used this option i could not use my finger for a week

so is there a way to set this automaticly?
if yes how do is set the settings for the mass mail

or is there a nice modification for it
if yes please post the name or link