8 Factors Governing your IP Reputation: Increasing Email Marketing Deliverability

January 12th, 2015

Getting your email marketing messages into your recipient’s INBOXes is key to a successful mailing campaign.  This is “deliverability.” One of the central factors governing the deliverability of your messages is the reputation of the Internet Protocol (IP) Address of your sending email server — its “IP Reputation.”

Here you can learn how to manage 8 factors that affect your server’s IP Reputation in order to maximize your reputation and increase the number of eyeballs that see your marketing email messages.

But first, you may want to check to see if you are on any common blacklists using mx toolbox.

1. How many messages has your server sent?

If your server has not sent lots of email before, then it is a relative “unknown” out there in the wilds of the Internet.  It has little or no existing reputation.  This is Ok … as long as you do not suddenly start blasting out huge amounts of email.  That would be seen as a “red flag” to filtering services and cause your server’s reputation to go down and for your server to be black listed.  E.g. your server would look like some machine on the Internet that was compromised by a spammer and which suddenly started spouting as much spam as possible.

Your best bet is to “warm up” your server’s IP address.  Send small mailing blasts of a few thousand messages at a time.  Slowly increase the size of your mailings over the course of a few weeks.  This serves to introduce your IP to the world in a smooth and cautious way that spam filtering services appreciate.

2. How many of your messages have been marked as Spam by your recipients?

Recipients who don’t really want your email will often mark it a spam rather than unsubscribing or deleting the messages.  This, unfortunately, makes it look like you have sent them spam — even if they subscribed to your mailings!  The more this happens, the worse your IP reputation can become.

You should subscribe to “Feed Back Loops” (or use a mailing service that includes) so you can be notified when folks do this; you can unsubscribe anyone who complains of your email in this way, preventing them from complaining in the future and thus minimizing the number of complaints (legitimate or not) against you.

3.  How often is your server trying to deliver email messages to invalid email addresses?

Even well maintained mailing lists may contain some email addresses that are invalid, as people change addresses frequently.  However, purchased email lists, old lists, and lists gotten via methods other than through the use of good subscription practices, will often contain large numbers of invalid addresses.

If your server tries to deliver messages to significant numbers of invalid addresses, that will be noticed and your reputation will go way down — your server will look like it is run by a spammer.

So — use new opt-in lists and make sure that you remove addresses that are bouncing right away — so that you do not keep trying them over and over on every mailing.

4. What is the rate that you are trying to deliver your messages?

Faster is not always better.  The more messages you try to deliver in a short time, the more likely your recipient servers are going to put up walls to throttle your sending or block you altogether.  Many recipient domains, most notably Yahoo!, have explicit low limits on the number of messages they will receive from an IP address in a given period of time. If you try to push beyond that, you shoot yourself in the foot.

Best is to (a) deliver the messages more slowly and (b) use multiple servers and thus multiple IP addresses in tandem if you need to increase your mailing throughput without tripping on recipient rate limits.

5. Has your server’s IP address been blacklisted anywhere for sending spam or other types of unwanted email?

If your server is blacklisted anywhere, that significantly decreases your IP Reputation.  You should work to get your IP address de-listed from any blacklists it is on and seek to ensure that your mailing patters do not land you on any new black lists.

6. Is your IP address static and set up properly by your ISP?

If you are mailing from a server at an ISP (e.g. Verizon, Comcast, cox, etc.) or from a virtual machine in the public cloud (e.g. Amazon, Rackspace, etc.), then your IP reputation is automatically lowered because that IP can be used by many different people over time and can often change hands without notice.  Be sure that your sending IP address is not changeable (dynamic), not owned by your ISP and not in a public cloud.

Also, make sure that there is a valid “Reverse DNS” entry for your IP address and that that matches the hostname of your server.  E.g. if your server’s name is “joes-mailer.com” then “joes-mailer.com” has a specific IP address (e.g.  If you look up what name goes with “” it should say “joes-mailer.com” and when your mail server talks to other servers it should say “Hello, I’m joes-mailer.com”.  If these things do not all match up, then your server’s IP will look “sketchy”.

7. Are other people using your server for sending email?  What are they doing?

If you are sending email through a server shared with other people, or the mail is going out trough IP addresses that are not dedicated to you, then you are not in control of our own reputation.  These other folks could suddenly start sending spam, degrading the reputation of the IP that you use, and harming the deliverability of your messages.

The best solution is to have a dedicated mailing server … once that is used only by you.  In this way, you can control exactly what gets sent through it.  You are in control and there should be no surprises.

8. Have others used your server or IP before you?  What is their legacy?

Lets say you just set up or got a new server and a new IP address.  This IP address was likely used by other folks before it was assigned to you … if these folks were not good custodians, your could have been assigned an IP address with an existing poor reputation!  If that happens to you, your best bet is to either get a new address or to:

  • de-list the IP from any black lists
  • wait a few weeks before you use the IP for your own mailings
  • warm up the IP by sending small mailings of solid non-spam-like messages to known good mailing lists

This should bring the reputation back up to good standards.

When it comes down to it, your IP reputation is based on your mail server provider, your configuration, and your behavior.  You can pick a good provider, proactively control your behavior, send good messages to good opt-in mailing lists and have excellent deliverability.

Try LuxSci’s email sending service for free; see how an excellent IP reputation affects your delivery success.