As marketers, we often take for granted the technical complexities that take place when sending an email from one address to another. We are so accustomed to pressing a button and having thousands, if not millions, of emails sent to their intended destination, with no questions asked.
If we do have issues in delivering those messages, we are often told (typically by yours truly) that the reason for non-delivery is reputation related, and that there is work to be done on the sender’s behalf in order to improve. However, there are times (albeit it rare) that the non-delivery of an address has more to do with the ISP than it does the sender. This is typically where the mystery of the valid/invalid address comes into play.
Determining when an address is valid or not all goes back to the bounce code that ESPs get back from the receiving domain. Those domains will almost always let us know if the message was delivered or not, and if the message was not delivered, they typically tell us why.
When the ESP receives a message that includes a specific “5xx” type error, coupled with a description such as “User Not Found”, “User does not exist” etc. that’s how we know that the address itself is no longer reachable, or doesn’t exist. The platform then considers this a Hard Bounceback, and as a result, we mark the domain as invalid.
As a brief refresher, the reason we mark that address as invalid, is to prevent further harm to a sender’s reputation when mailing to that domain. Sending mail to addresses that no longer exist is a big time no-no in the eyes of ISPs.
Therefore, taking away the ability for a sender to mail to those addresses moving forward, is a proactive way of protecting that sender’s reputation over the long haul. If they were to continue mailing to a wide array of those types of addresses, reputation and ultimately inbox placement would suffer immensely.
The issue here is that sometimes domains do make mistakes in terms of what they are telling us within the bounceback message. This is where we run into the scenario, where valid addresses are marked as invalid by the platform that is sending them mail. Essentially, all domains/ISPs are recommended to adhere to RFC guidelines outlining how SMTP error codes are handled during sending/receiving of email.
Those guidelines are outlined here. These guidelines clearly define how mail systems should be sending bounces back over the internet. Domains who choose not to follow these defined best practices will continue to cause these types of mis-categorization issues. In other words if a domain sends an ESP back an error that looks like a Hard Bounce, then the ESP has no choice but to process that as a Hard Bounce and mark that address as invalid.
If the ESP did not, it then runs the risk of letting its sender’s mail to a high number of invalid addresses, which would completely ruin their sender reputation. The risk of doing that far outweighs the reward of salvaging just a few valid addresses.
So now that the mystery is solved as to why these addresses get marked invalid when they are in fact valid, let’s focus on what you as a sender can do about it in order to protect that customer experience that is so valuable to a successful email marketing program. First, it is important to understand where this scenario is most likely to occur.
Typically, we see this take place when mailing to smaller, private, domains such as businesses, .edu, .gov, etc. This is because those domains simply don’t have the same type of buttoned up infrastructures like the Gmail’s, Yahoo!’s, and Hotmail’s of the world. If you see this take place at one of these smaller domains, your best bet as a sender is to get confirmation that the address in question is in fact valid, and then reset their Deliverability status to valid within your platform’s UI.
If you as a sender are in direct communication with the customers who were accidentally marked as invalid (they do often report this into a call center to complain they are not receiving emails), we recommend reaching out proactively to these customers and advising them to raise these issues to their internal IT teams. This way those teams can work internally to prevent this issue from happening again in the future.
This will show that you as a sender are willing to go the extra mile to ensure that the individual’s customer experience is a good one, which will only strengthen your relationship with that customer moving forward.
Another item to point out is that even though that address bounced and was classified incorrectly, the fact of the matter is that the address is still bouncing in the first place. This means that there are likely bigger problems going on at the domain you are experiencing this issue at.
There is likely a reputation based block taking place, and it will be important to adhere to all relevant best practices moving forward when mailing to that domain. Doing so should decrease the extent of the bouncing, and prevent the problem of the Valid Invalid address from occurring in the first place.
At the end of the day, a few valid addresses being marked as invalid at smaller domains, is going to happen from time to time. Senders who ensure they are following best practices when sending out their daily marketing campaigns, will minimize this quite a bit.
However, if reputation is already an issue, a few addresses being marked incorrectly is more of warning of a bigger issue that is taking place and impacting deliverability. Doing your due diligence as a sender to resolve those larger issues to prevent smaller ones should always be top priority!
According to research over half of all emails are opened on a mobile device. Unfortunately, all the work we do to ensure our emails render flawlessly on the desktop doesn’t take into consideration how these same emails will show up on a smaller screen.
Download the Mobile Email Guide to learn how to improve the mobile marketing experience for your customers.
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