Outlook 2007 e-mail help

When I send e-mail to some addresses I get error 553 the domain isn't in mhy
list of allowed rcphosts #5.7.1
I will appreciate any help with this problem

Outlook questions should be posted to one of the outlook groups.
Outlook is part of the Office family, not win*

"Carolyn" <Carolyn@discussions.microsoft.com> wrote in message
news:37F8DB68-E02E-4F46-812D-4444F06BB0A9@microsoft.com...
> When I send e-mail to some addresses I get error 553 the domain isn't in
> mhy
> list of allowed rcphosts #5.7.1
> I will appreciate any help with this problem