my machine is macbook pro lion , i am using micros soft outlook, internet connection is via talk talk, this problem just came out of nowhere, and emails seem to be getting delivered thanks for your help
Relaying to <the email address> prohibited by administrator Email could not be sent Account name (my account name) Error -17099
Error -17099 is an Entourage error kSMTPServerReplyErr, and is returned when the SMTP server has returned a permanent or transient error or returns an unexpected result code.
This error is coming from your ISP.
Users have reported this error when sending to large groups. ISPs limit the number in a group. Usual number is 50 recipients to avoid spammer misuse. Entourage has no limit. You should contact your mail provider to ascertain the maximum number of recipients per message and note it. You can use the free "Split Recipients" script to send a mass e-mail in separate mailings automatically: