Yahoo bounce message: 550 5.7.1 [BLXX]

Connections not accepted from IP addresses on Spamhaus

"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.

Stop all this jibber jabber, what does it mean?

Either your IP address, or your SMTP server IP address is blacklisted on spamhaus.org. Yahoo is no longer accepting email either from your computer, or from your SMTP server. This is a permanent error that needs action from either you or your SMTP server administrator (depending on who is on the blacklist).

Did I do something wrong?

Perhaps; if it is your personal IP address that is blacklisted, then yes, although if you are certain you did not send spam, your computer may be infected with a virus or Trojan Horse. It may also be that the problem resides at the SMTP server you are using in your email software; in that case, it is the SMTP server IP address that is blacklisted and not your personal IP address.

How can I fix this?

Check if your IP address is blacklisted: http://www.spamhaus.org/query/ip/3.95.139.100 (we already included your current IP address in the previous link). If it is listed, make sure you fix the problem first before you ask for removal on this website. If you are certain you did not send any spam, scan your computer for possible virusses, worms or Trojan Horses and make sure your computer is no longer infected. After that, you can ask for removal on this website. Removal usually takes one or two days.
If your IP address is not listed here, check if your SMTP server is blacklisted instead. You can find your SMTP server address in your email software settings. Copy this address and go to: http://www.spamhaus.org/lookup/. If it is listed, contact your SMTP server administrator and let him / her ask for removal.