Individual e-mails rejected when trying to send group e-mail

[Chris Cullen]

I am trying to send a group e-mail to a Windows Contacts group. It is
rejecting individual e-mails (not all, but many) and the error message is:

The message could not be sent. The authentication setting might not be
correct for your outgoing e-mail [SMTP] server. For help solving this
problem, go to Help, search for "Troubleshoot Windows Mail", and read the
"I'm having problems sending e-mail" section. If you need help determining
the proper server settings, please contact your e-mail service provider.


When I go to the Troubleshooter it directs me to...

Click to open Windows Mail.

Click the Tools menu, and then click Accounts.

Under Mail, click your e‑mail account, and then click Properties.

Click the Servers tab, and then, under Outgoing Mail Server, select the My
server requires authentication check box.


....which I did.

Individual e-mails (which are all good addresses) are still being rejected.

Any ideas about what is wrong? There are 380 e-mail addresses in this
contact group and I have successfully sent e-mails to this group before.

 

[Chuck]

Your IP may have imposed anti-spam measures limiting the number of emails
sent at one time, or within a period of time.

 

[Gary VanderMolen]

That's just the preamble to the actual error message.
Right-click on your error message, copy, then paste it into a reply here.
We need the portion that has the server name, port number, etc.