Q: Hello EmailKarma,

Are IP address portable? If you are thinking of moving hosting facilities and have built your reputation on your IP address that is owned by a telecom company – how do you suggest handling this? If you can’t take your IP with you, how do you take your reputation with you? Any insight would be great.


A: After doing some research and talking with some other delivery experts to get their opinions on this, here is what we are able to suggest.

IP addresses are only portable if you “own” them (were allocated them by ARIN or RIPE or whoever). To get IPs that you own and could move from one provider to another you would need to be using at least a /21 (approximately 2,000 IPs).

A few ISPs (Hotmail specifically) have said, that they are now able to transfer reputation between IPs if they are published in the same authentication records with the old ones and that you continue to send email from. After your reputation is established you remove the old from the record and keep the new ones in there while you use the new system or IPs.

There was also discussion about the benefits gained from the reputation of your Domain Key (or DKIM) selectors and mailing history, that allow you to move reputation based on these keys and the past performance associated to them. Basically if an authentication technique can be tied to a domain and the reputation is based on that domain, then reputation should be portable. The problem is that, most reputations systems are still evolving and many still focus on the IP address.

Early in September EmailKarma answered the question Whats the best way to build reputation on new IPs? Using these suggestions and migrating your mail from one Network paired with the information above will give you the best results for moving your reputation from one IP address to another.

Do you have a question for EmailKarma? Email them to contact or leave a comment.

Special Thanks to Steve, Dennis, and Jeff for their insight and opinions