This article will describe what actions you can take when presented with the following SMTP errors:

• "550 5.7.1 [BL21] Connections not accepted from IP addresses on Spamhaus PBL"
• "550 5.7.1 [BL22] Connections not accepted from IP addresses on Spamhaus SBL"
• "550 5.7.1 [BL23] Connections not accepted from IP addresses on Spamhaus XBL"

In our continuing efforts to protect our users from unsolicited email, Yahoo! Mail does not accept SMTP connections from:

• Dynamic or residential IP addresses as determined by Spamhaus PBL (Error: 550 5.7.1 [BL21])
• IP addresses listed as spam sources on the Spamhaus SBL (Error: 550 5.7.1 [BL22])
• IP addresses listed as a possible open proxy or spam-sending Trojan Horse on Spamhaus XBL (Error: 550 5.7.1 [BL23])

If you are seeing this error message, please do not retry sending your message using the same IP address.

If you think that your IP address has been listed in error, you or your email administrator should contact Spamhaus. Once your IP is delisted by Spamhaus, Yahoo! Mail will automatically unblock your IP within 48 hours.