Cannot Send an Email from My att.net Account

I can receive all of my att.net email just fine on multiple platforms. However I cannot send, forward or reply to any messages from the same email account.

The error message I get when I hit send is: "Your message cannot be sent because it resembles spam and/or contains only links. Please modify your message and try again."

I have tried sending simple messages with just a few words, empty emails, and emails is absolutely no links. Nothing seems to work.

What am I missing??  Has my account been locked out for sending any messages?

Thanks for any help