Sector 5 policy reasons

I have a question about a problem I am having with using gmail to send mails. No matter what I do, if I send it to more emails at a time, it gets rejected for "sector 5 policy reasons".

This is an automatically generated Delivery Status Notification
Error message:

Technical details of permanent failure:
PERM_FAILURE: Message rejected for Sector 5 policy reasons

I know the limit used to be 200 to 250 a day.So I am using other SMTP services But also there are a lot of delivery Failure Notice with the same reason.Also This error is generated by messages sent to ANYWHERE... IncludingHotmail...
when sending an email from Outlook/ Outlook Express using the one other smtp server i get this error whenever i send an email to some domain that is not on my server:

This is an automatically generated Delivery Status Notification
Error message:

553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)

I can't find anything about Sector 5. I can't find any way to contact Google.Can anyone suggest me???????