I keep getting email I am sending bounced back with this message
SMTP error from remote mail server after initial connection:
host mx1.bt.mail.yahoo.com [195.50.106.142]: 553 5.7.1 [BL21] Connections will not be accepted from 91.208.99.47, because the ip is in Spamhaus's list; see http://postmaster.yahoo.com/550-bl23.html