Most, if not all, of the large ISPs judge your reputation largely based on the feedback they receive from their users regarding your mail. Generating too many complaints over a period of time puts you on the fast track to getting blacklisted.

Let’s look at Yahoo. Getting email to Yahoo recipients is always challenging. If you are getting any one of the following errors it is most likely due to user complaints:

451 Message temporarily deferred - [numeric code]
421 Message temporarily deferred - [numeric code]
421 Message from (x.x.x.x) temporarily deferred - 4.16.50

Yahoo seems to be dynamically blocking IPs based on user complaint rates, however the good news is that they have been automatically releasing these blocks in relatively short time, i.e. a few hours. Other ISPs might not be so quick to forget. And in any event, even a few hours can really set you back.

Solving this problem is really no different than what email marketers should be thinking about anyway, and that is how to lower user complaint rates. There are several things you can do right now to reduce your complaint rate and I will cover them in this post.

Frequency / Content

Many studies have been conducted in this area and user complaint rates seem to be controlled by two factors: a) the content of your message b) the frequency of your message. And there is a relationship between the two factors: the message content will affect the frequency one is willing to accept.

If you are sending out a coupon to your entire list every day this is most likely going to generate complaints. If, however, you are sending important alert messages – alerts which are deemed important and valuable by the recipient – this may be perfectly ok.

The bottom line here is not to annoy people – it is that simple.

Removal Process

Another item you should always consider is the removal process you provide to your recipients. You can lower your complaint rate by simply providing an easy to use removal link in your message. Also include your mailing address and phone number. Not only does this help you comply with CAN-SPAM, it also signals to your recipient that you are not trying to conceal your identity or misrepresent yourself.

Recognition & Relationship

Send email only to people that will recognize who you are and recognize their relationship with you or your business. If you have no relationship with a recipient, they will most likely consider your email spam. Furthermore, in this situation they have no basis for trust and are far more likely to report your mail as spam rather than follow your removal instructions.

Slow Down Your Delivery

There are always going to be some complaints no matter what you do. Complaint rates are usually based on the number of complaints over a period of time, Slowing down your delivery will spread the complaints out over a longer period of time and therefore reduce the overall complaint/time ratio. Products like Hurricane Server and SMTP Express Pro enable you to shape traffic to specific domains and you can use this functionality to throttle back delivery to certain domains like yahoo.com to instantly reduce your complaint/time ratio.

Spread Out

Complaints rates are usually aggregated by the IP address that generated the email. By spreading out your messages over multiple IPs you can decrease the number of complaints per IP overall.

One issue you should take into consideration, however, is the effect this will have on greylisting. Greylisting systems will often whitelist your IP/sender/recipient combination once you get a message through. This goes a long way to increasing future delivery rates, however if you send the same sender/recipient combination over a different IP, that whitelist may not apply and your message will be greylisted once again. You simply have to weigh the pros and cons of this approach.

All of the Above

Each one of these tips will decrease the complaint rate and thus improve your deliverability and reputation. When they are all used together they become synergetic and will go far to increasing your deliverability by reducing your complaint rates.