By: Jake Hoiby, Sr. Manager – Email Deliverability | 11/19/2019
Why doesn’t email just work?
We are used to personal email being pretty reliable. Deliverability won’t even cross your mind when sending a single email to a friend or family member. Comparatively, reaching the inbox with high volume marketing email has a few more dependencies:
All these differences increase the potential for deliverability issues. So if deliverability for marketing email is more complicated, how do you as a sender determine the actual cause? Narrow down the potential causes by determining where the sending process broke down. For most senders, having an email deliverability issue usually means “I expected an email to be sent, but it’s not in my recipients inbox”, so for practical purposes you can consider the breakdown to be in one of three places:
Was an email actually sent to the contact?
If you can see a delivery or bounce event for the contact in the particular campaign in question, that’s a clear indicator that your email was actually sent, and you can move on to the next question. If you can’t find evidence of a delivery or bounce, you’ll want to check a few assumptions:
If everything looks correct but you have no evidence of a delivery or bounce, consider that the email could still be pending. There’s a lot going on behind the scenes so it’s appropriate to have a different set of expectations for marketing email vs single person-to-person email. Most marketing automation systems have to process huge volumes of email, which can take some time, especially during peak hours. Even if the sending server attempts to send immediately, the recipient servers have their own rate limits and outages, so for various reasons some email can be delayed for up to a few days.
Was the email delivered to the recipient’s email server?
If you have evidence of a delivery event, you can move on to the next question. If the email failed to deliver (bounced), you’ll want to investigate to see if there’s anything you can do. Bounce messages will usually contain a code that indicates why the email was not accepted, but interpreting bounce messages can be tricky. There is a standard set of bounce codes, but not all recipient email servers adhere to the standard, though major networks will often have published information on their unique bounce codes. In addition to the codes, the accompanying description should provide context, but if it’s still unclear, searching the net for phrasing from the codes (leaving out any unique information like the sender/recipient address or your sending IP) will usually help to decipher them.
Below are some common bounce messages that provide actionable insight. Note that these are just examples, the actual wording can vary widely depending on the recipient server.
Poor Sender Reputation:
Recipient Side Issues:
Through our experience with personal email we’ve come to expect email to work right away, every time, but this doesn’t hold true for high volumes of marketing email. Some types of bounces are normal shouldn’t be considered a problem unless you’re seeing them in high volumes.
Was the email delivered, but not placed in the inbox?
Since this decision happens on the recipient side and after “delivery”, we usually don’t have any information which makes it harder to determine the root cause. Look at bounce messages from the same campaign for any indication of a systemic issue, as some recipient servers will reject (bounce) an email for the same reason that others will junk it. Without any useful information, the best approach is to address each of the potential causes:
Manual filter / inbox provider personalized filter
Out of band bounces
The Cumulative Effect
Deliverability factors can be additive, meaning that while some minor problems may not solely inhibit delivery, they may do so if they occur in conjunction with other problems. Keep in mind that there could be multiple causes, so the best approach is to make sure everything is tip top - don’t ignore the potential impact of seemingly minor problems.