Email delivery can be a very tricky business. You have to accept that with every bulk email message you send out to your list, you're bound to get at least one bounce, or worse yet, end up in a spam folder or two. Even the best email marketers encounter this.

Troubleshooting Email Delivery

However, before you panic with the thought of losing the credibility of your email list, you should check out the following tips and hopefully they'll improve your delivery rate this time round. Troubleshooting email delivery is definitely a manageable task :)


You'd be amazed at some of the things that cause your email messages to end up in the spam folder. Content is just one area that's difficult to troubleshoot. Everything ranging from phone numbers to URLs to certain mailing addresses can cause your emails to be flagged as spam. And aint nobody got time for Spam!

Also, some ISPs have been known to reject emails that contain poorly written code. So if you must use HTML or Heaven forbid ... Javascript! ... ensure it's well written and compliant. You also want to avoid the use of too many large images.

Secondly, you may get a failed delivery notice when you've included a URL shortener in your email body. The domain or source IP for most of these service are abused by spammers, and will often appear in multiple email black lists. Certain cloud services such as AWS are prone to rejection as well. For this reason, you should always use a service that has a good reputation.

Your sending reputation

One of the factors that ISPs use for their filtering decisions is your domain and IP reputation. If your reputation is negative, you'll be blocked in the worst case scenario. In fact, the more you send emails, the more your reputation can deteriorate. For this reason, it's always advisable to scrutinize your email campaigns on a regular basis. is one place to check your reputation and see if there's any issues.

Your complaint rate

It's tough to troubleshoot email delivery without knowing your complaint rate. There's a few things you should do here:

  1. Make sure your emails are highly relevant to your readers to avoid people getting annoyed and clicking the Spam button on ya.

  2. Setup Feedback Loops. Sign up to start receiving complaint data from the top ISPs and email providers. Once you receive these notifications, you can begin weeding out offending email addresses (those who report you) from your list of subscribers. This practice will boost your domain / IP reputation, because you'll get less spam reports. Winning!

You could be blacklisted

A high complaint rate will get your domain and/or IP blacklisted faster than you can blink an eye. And when this happens, ISPs will block your email messages from reaching their intended audience, either by bouncing them back, or routing them into spam folders.

If you want to know whether or not you've been blacklisted, here's a great place to start:

They'll check over 100 blacklists for you! If your IP does appear on any blacklists, MXToolbox will provide the link to request a de-listing. Some blacklists have stricter de-listing requirements than others, such as you sending them an email explaining your case and apologizing. Yeah, this process isn't fun for anybody, but it's the price you pay for breaking the rules ;)

Have you authenticated your emails?

This feature lets you "sign" your emails, which makes them look more legit. Authenticating emails goes a long way to making the work of spammers and phishers more difficult, since they can't use brand names to trick ISPs and unsuspecting users into clicking their spam emails. The most important thing to remember here is that if you don't authenticate your emails, some ISPs will mistakenly send you to the junk folder.

At a minimum, we recommend setting up SPF and DKIM.

Hope these tips help, good luck winning your email campaigns!


Kane Miller from Winning.Email

Kane has a background in computer engineering, but now focuses on creating new and interesting web services. His passion for improving his own email deliverability rates was the driving force behind the creation of Winning.Email.