Shared vs. dedicated IP: don’t let unscrupulous senders slander your reputation.

Posted by bkloss | Email Deliverabilty | Friday 8 February 2008 12:29 am

You’re a good email marketer aren’t you?

Why yes, I use double opt-in, white-listing, permission based sending and a host of other best practices yet I’m still being blocked by some ISPs.

What you may not know is, regardless of all these tactics, unscrupulous senders can besmirch your good name effecting your relationship with ISPs.

As an email marketer, your reputation (good name) is one of the most important determining factors for deliverability. ISPs attach reputation to the IP of the mail server you are using to release campaigns. Sending IP is analogous to the concept of a gentleman’s good name in the day’s of old. Be true to your word, pay off debts and treat others fairly and the local towns folk will look on your name with esteem. On the other hand those who engaged in slander and unscrupulous behavior found that a stigma was attached to their tarnished family name.

Sounds easy right?

Well, many small and medium sized email marketers are not aware that their third part provider is sharing their IP amongst several clients. If you are sharing an IP, the shady practice of your IP neighbors can have a detrimental effect on all your efforts.

I recommend getting a dedicated IP so you have more control over your own reputation. This is only "worth it" if your list is generating enough revenue to justify the start-up cost($100-$500) and monthly ding ($100 or less) of a dedicated IP.

Another route is to ensure that before you sign up with a provider, make sure your soon to be shared IP is used by good neighbors. ESPs will dig into your prospective neighbors if you ask and produce a report.

I recommend that you request records for:

  • Spam complaint history
  • Black listing
  • Deliverability in general
  • Opt-in practices

of all your soon to be neighbors.

Although a deicated IP will afford senders more control, it is not the silver bullet that it is often portrayed to be. Malia Herold of EmailKarma roped in leading experts to explain the effect of dedicated IPs. I’ll sumarize below.

It appears that having a dedicated IP may not shelter you from unscrupulous practices of other neighboring IPs. Some IPSs block domains at the C level. C blocks are sold in packs of 256 IPs so as long as yours is one of the pack you will still be effected. many IPSs use an escalated blocking system. At the first level only one IP will be effected but, depending on the severity and frequency of infractions, this can be escalated to include large groups and eventually C level blocks. For more information, see Email Karma’s article.

Having a dedicated IP is only appropriate if your sending practices are optimal. With a static, dedicated IP you are totally responsible for your activities. ISPs will come down on you hard because they, depending on their blocking strategy, can effect you alone. If you share an IP there is a diffusion of responsibility effect where IPSs may treat infractions more lightly if they know blockage will effect all parties involved. If this sounds contradictory to what was said above, you’re right. It is important to remember that blocking practices and penalties will differ across IPSs. Just remember that you should ensure that all your practices are top notch before considering a dedicated IP.

According to Mark Brownlow another reason to use a shared IP is sending volume. Some ISPs specifically AOL and Hotmail) will assign your IP a low reputation if they are not receiving and accepting a high volume of mail. Again, results will vary but if your list is only a few thousand strong, I would recommend sharing an IP with good neighbors to pool your volume.

The good news is, one day the dedicate/shared IP debate may be obsolete. IPSs are aware of the problems created by attaching reputation to a sending IP. So, recent authentication systems such as Domain Keys are attaching reputation to a sending domain. If IPSs can implement a domain based reputation system, we senders will truely be incontrol of our good name :)

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