Posts to mailing list still being rejected.

[Minnesota Slinky]

Hey all,

I sent an email a couple weeks ago about my posts
being rejected with a 550: Message Content Rejected. 
Someone directed my to www.ordb.org and pointed out
that the IP address of the mail server I'm using was
listed as an open relay.  I've now taken measures to
remedy this, as displayed here: 

http://www.ordb.org/lookup/?host=216.136.204.125

Alas, my posts are still being rejected with the 550:
Message Content Rejected.  Giving up on
216.136.204.125.

Please help me!

TIA

Eric