Improve Your Email Delivery Rates


In a recent article I wrote, I addressed some of the issues with avoiding spam filters and improving your email deliverability rates. Today I’m going to delve a little deeper and give you some more ideas on how to increase the number of emails that actually get delivered to your subscribers.

Is your domain’s IP address blacklisted?

The first thing you should check if you feel there’s something suspicious about your deliverability rates is your domain’s IP address against spam black list databases.

These databases store the I.P address of domains that have been known to spam. ISP’s and email administrators can use this data to block further emails being sent from that domain. In some cases, someone may have used your IP address to send out spam emails, or your emails may have been reported as spam even though they weren’t.

If you’re unsure what your domain’s IP address is, simply open up a command prompt in windows (start menu -> run -> ) and type in ping . You should see something like this:
Pinging [] with 32 bytes of data:
Your IP address is contained inside the brackets (in this case the IP address is
Once you’ve obtained your IP address you can start checking it against the different black list databases.

I’ve supplied some of the more popular ones below:

You can find a more comprehensive list by clicking on the link below:

If you’re IP address isn’t found on any of the lists, then great. If it is you can try to contact your ISP and find out if you can get a new IP address. You can also try contacting the owner of the blacklist site to get your IP address removed from their database. Watch your attachments
Many people don’t realize that the type of attachment you send with your email can cause different spam filters to block your email and even go so far as reporting your I.P to a black list database.

You should avoid using script or any type of attachment besides PDF. Many corporate mailboxes as well as virus filters block attachments that end in .exe, .avi, .swf, .zip, etc.

Make sure your server is configured for reverse DNS lookup

Reverse DNS lookup, originally designed as a network troubleshooting tool, has become an import tool in the fight against spam. When an Internet mail server receives an email it receives an “SMTP” greeting. This SMTP greeting is how the 2 servers communicate with each other when sending and receiving emails.
In this SMTP greeting, the sending server identifies itself as with an IP address of (for example). The receiving server can now do a reverse DNS lookup, to see if the IP address actually matches the domain name. A lot of spam servers won’t match and so the receiving server can mark this as one failed test on a list of many to indicate if the email is indeed spam or not.

Most reputable hosting companies should already have this configured, but it doesn’t hurt to ask. If your server is not configured for reverse DNS lookup, then be very wary of sending legitimate bulk email from that server. Don’t send bulk emails using the BCC field.

Some of us using our favorite email client (such as Microsoft Outlook) tend to send mass emails using the BCC field. That’s okay if you’re forwarding something of interest to your friends or co-workers, but don’t ever do this when sending your newsletters.

Using a BCC field is another trigger for spam filters that you want to stay away from. Instead, your email program should send just one email to one subscriber at a. Don’t fall into the trap of thinking it’s a good idea to send your newsletter to 200 subscribers using the “CC” and “BCC” fields. Keep your lists as clean as possible.

Honor all unsubscribe requests (your email marketing software should generate an unsubscribe link for all emails you send) and process bounced emails frequently. Sending to email addresses that have bounced repeatedly can result in a blacklisted IP address. You want to make sure that each bulk email you send does go out to legitimate, working email addresses.

You should also make sure your abuse@ and postmaster@ emails are valid and working. The Internet Engineering Task Force (IETF) has recommended these email addresses for complaint spam reporting and you may receive emails from users or ISP’s if they have a complaint or spam report about your mailings.
Let your subscribers know when your emails are coming.

If you offer a subscription to your newsletter from your web site then tell each and every subscriber exactly when to expect your newsletter. For example:
“We send our newsletter once a month, usually around the 20th, so make sure you keep an eye out for our next issue!”

Also, if someone has subscribed for your newsletter and only your newsletter, don’t go sending them special offers and other unrelated emails unless you’ve told them to expect to receive them.

For example:
“When you join our mailing list we may occasionally send you special offers for our products and services, but don’t worry – every email includes an unsubscribe link if you change your mind.” Use double opt-in lists
I’ve mentioned this in my previous article but once again to make your mailing list as clean as possible always use double opt-in strategies. That is, when someone signs up they should receive an email which contains a link they must click to verify that they do indeed want to be on your mailing list. This stops illegitimate email addresses from being added to your mailing list. Let subscribers update their details.

If I switch jobs or change my email address, I should be able to come to your web site and change my newsletter subscription from me@ to me@ using a simple “modify details” form. By allowing your subscribers to do this, you reduce the number of bounced emails and keep your subscribers active much longer.

Conclusion Improving email deliverability is one of the toughest tasks for any email marketer. While this list is by no means complete it can dramatically help to improve your email deliverability and hopefully your click thru rate and bottom line. Until next time, best of luck in your e-marketing efforts!