Email Blacklist Checker for IPs and Domains

Why a blacklist listing hurts

A DNSBL, or DNS-based blackhole list, records addresses known for sending spam. Once your mail server's IP appears on a major one, the messages you send start bouncing or landing in junk folders, often with no warning at all. Gmail, Outlook and most company mail systems check these lists live before they accept a message.

Common reasons an IP gets listed

• A hacked account on the server was used to send spam.
• A mailing list without confirmed sign-ups reached spam-trap addresses.
• SPF, DKIM or DMARC records are missing.
• Another customer on the same shared server misbehaved. This is less common, as most hosts keep outbound IPs apart.
• Mail is going out from a dynamic or residential IP range.

What to do if you are listed

1. Deal with the cause first: lock down any hacked accounts and publish SPF, DKIM and DMARC.
2. Ask each list to remove you. Most offer a self-service delisting form.
3. Keep checking for 30 days afterwards in case you are listed again.

We watch every SiteBoma outbound mail IP around the clock and ask for delisting straight away if one is ever listed.