Can't send messages from Outlook to multiple mail addresses, I even can't receive mail for an hour! What is happening??

Question

I was forced to stop using Windows Live Mail and step over to Windows Outlook. I had problems enough with Live Mail, but Outlook is worse... After a lot of trying I managed to make a list of (295) contact persons to send messages to. But Outlook doesn't accept my outgoing mail and refuses to deliver. Even if I split the amount of addresses in two. Outlook says something vague about 'exceeded hourly rates' (?). The information is really terrible, I can't figure out what the real problem is! The only information I have is that Outlook refuses to deliver the message I sent and doesn't let me send any messages for an hour. And when I try it again after half a day, to only one contact, it also won't deliver. Why can't Microsoft send me the real reason of what I'm doing wrong (from their perspective) and HELP ME OUT???