email list to group of friends has started failing

I have 2 lists of less than 50 email addresses each for a school class reunion/newsletter. I send them from [email protected] for my wife. When I sent the email (as BCC) all the messages bounced back. All of them. I get two types of messages:

[email protected]
host smtp.servconfig.com [173.231.200.191]
SMTP error from remote mail server after end of data:
550 High probability of spam

[email protected]
host smtp.servconfig.com [173.231.200.191]
SMTP error from remote mail server after end of data:
550 High probability of spam

[email protected]
host smtp.servconfig.com [173.231.200.191]
SMTP error from remote mail server after end of data:
550 High probability of spam

OR

Action: failed
Final-Recipient: rfc822;[email protected]
Status: 5.0.0
Remote-MTA: dns; smtp.servconfig.com
Diagnostic-Code: smtp; 550 High probability of spam

This has never happened before. I send this out to this list on a quarterly basis. I need to be able to send out these emails. I am with the 50 address limit inch email. This looks vey much like it is coming from my server. What can I do to correct this? And please do not tell me that I cannot send to more than 1 or 2 people at a time.

Best, Scott