Email Marketing News and Tips

At Boomerang, we have a number of customers contact us with similar questions regarding what’s discussed in this blog article.  This article will discuss the many different reasons why mail appears to be delivered, but doesn’t arrive in the Inbox during an email campaign. I should preface this article by stating that SMTP is an unreliable protocol (and it was designed that way).  There is no guarantee that any piece of email will be delivered.  Once Boomerang receives a an SMTP success code (250), Boomerang concludes the email was delivered based on RFC specifications.  This article is also intended to help provide you with expectations in this process.

Successful Send

When Boomerang receives successful completion of the SMTP dialog all the way through to the ‘250 Email Queued for Delivery’ message, this usually means the email was delivered.  This final return code indicates the mail server accepted the mail and it is assumed to route the email to the user’s Inbox (or into one of the user’s folders).

Gone, however, are the days where 250 actually means what it says.  Instead, there may be layers of filtering and other plug-ins between the SMTP interface and the user’s Inbox.  Thus, there is still a possibility that Boomerang will receive a fully successful delivery status, but the email doesn’t get delivered, is quarantined or is dropped on the floor.

Failure Codes

Boomerang also receives other error codes during sends that can indicate issues or lack of delivery.  However, many of these failure codes are also normal failures.  Some codes are as follows:

• 421 - Temporary failure.  This code is usually denotes deferred deliveries to a later less busy time or it could mean the remote servers disk is full or CPU is overloaded
• 450 - Mailbox unavailable.  The mailbox is full or offline
• 550 - Permanent failure.  The user’s inbox does not exist
• 146 & 147 - Mail server timeouts.  These are internal error codes that our software generates if the SMTP dialog times out for any reason.  The 146 and 147 distinguish specifically when the timeout happens during the transaction.
• 160 - Connection Timed Out.  The mail server that we tried to connect to timed out during the connection.

SMTP error and success codes

The many SMTP RFCs that discuss the SMTP protocol are very explicit about the way errors should be handled.  Unfortunately, too many SMTP products today completely break the protocol and do not follow the RFC specifications.  For example, the 250 receive on a successful delivery should indicate the mail was placed into the user’s Inbox.  Unfortunately, many spam filtering products do not follow the RFC to make this happen.  Instead, they can sideline or delete the email even when Boomerang receives a 250 success code.  This behavior completely breaks SMTP’s reliability… not that it was fully reliable in the first place.

Some sites, like AOL, choose to accept all mail with a 250 success code, then turn around and bounce the email back (soft bounce) at a later time.

Receiving 550 ‘recipient not found’ on known good mailboxes

This problem is usually the result of spam filtering products.  This issue can be triggered because of the IP address or because of email content.  It is important to note that if you want to users to receive your email that you make sure they safelist your ‘From’ address before you send.  Note that safelisting doesn’t always get your email through server level filters, though.  Getting the email through may require additional configuration on the part of the mail server administrator.

Corporations

Note that corporations don’t have any requirements to follow any standards for email delivery.  Basically, corporations can do whatever they want to ensure corporate email is stable.  This means, mail administrators can delete whatever email they deem a problem (legitimate or not).  Legitimate email that’s deleted is known as a false positive.  False positives are common in corporations because of overzelous email administrators who wish to minimize their email management workload.  Managing an email server takes a fair amount of time to constantly tweak filters to give the best response at the same time minimizing unwanted email.  But, priorities change and the administrator lets the email server management slide, so false positives go up.

Unfortunately, the economy is taking its toll on all corporations.  As a result, staffing is being cut back, so email false positives are, in many cases, on the rise.  At the same time, the email server is at the bottm of the systems administrator’s list of priorities.

What can you do?

• The best thing to do is make sure your recipients are fully opted-in (preferably double opt-in).
• You should make sure that your Email Service Provider (ESP) has SPF set up to authorize the ESP’s IPs to send on your domain’s behalf.
• You should ask your recipients to safelist your From address.
• Double check your content for keywords that might trip a spam filter
• Finally, part of this will be trial and error.

You may still go through all of these suggestions and find that your emails are misrouted and do not show up in the user’s Inbox.  What do you do?

Ask your recipient to contact their mail server administrator and diagnose the issue.  They will need to explain that the emails are not being delivered.  The mail server administrator will need to do research to find out the issue.  In many cases, this issue is caused by spam filtering products either deleting or quarantining the email.  Quarantines are temporary, so this step will need to happen within a few days of the mail delivery to save the email.

Boomerang, as an ESP, can do some work on our client’s behalf, but since the list contains our client’s recipients, prospects or customers, it is our client’s responsibility as an email marketer to contact those users on their list directly.  When Boomerang contacts our client’s recipients, this can be a little offputting for both your recipients and for the company involved.  Boomerang can get involved when Yahoo, Hotmail, AOL and other large ISPs are involved.  However, when the problem involves a corporation, then it is you who should first contact your recipient to get diagnosis started.  In many cases, your recipient may already be aware of this issue and know a way to circumvent the blocking issues.  If not, they will need to contact their mail administrator and have them determine the issue.

Boomerang’s Delivery Services

Boomerang provides email marketing services to our clients.  However, when there is an issue, we cannot fix hardware or software that we do not control.  When issues involve our software or system, we can resolve and fix these issues with software fixes.  In even rare cases, we may even devise workarounds for remote issues. However, when an issue presents that involve remote computers that Boomerang doesn’t control, Boomerang cannot fix these systems.  For example, when we receive a 250 successful delivery message and the email doesn’t arrive in the user’s Inbox, this issue is out of Boomerang’s control.  This issue also indicates a problem on the remote side.  The best Boomerang can do is let our clients know that it’s a remote side issue and explain what may be happening. Boomerang has no control over those systems or how long it may take to get the issue fixed.

On the other hand, our client may assume that it’s a Boomerang issue even when it is a remote side problem. The unfortunate reality is that Boomerang cannot fix these remote systems that are not under Boomerang control.  We can give advice and offer ideas to help resolve the issue.  It is still up to the remote adminstrator to fix the underlying issue.

Again, for list related issues, Boomerang doesn’t contact client list recipients directly.  It is up to each client to contact their recipients to ensure proper continued delivery.  Boomerang will, again, give advice and direction on what to do, but it is up to our client to work through the issue with each recipient in their list. This is considered part of list maintenance that is up to each client to manage.

Client management and involvement

Boomerang enables email marketers with tools to help ease email marketing.  But, our tools do not eliminate the need for some list maintenance work on an email marketer’s part.  This means that there will still be a certain level of client involvement necessary to ensure list cleanliness and continued delivery.  Boomerang’s tools are best-in-class, but they are not fire and forget.  You, as an email marketer will still need to do some work to manage your lists to provide your continued business success.

Keep in mind that Boomerang does offer Professional Services staff who can provide certain services to assist in some of this work.  Keep in mind, though, that our Professional Services are fee based per hour.  We are glad to help you work through your issues when we are able with our Professional Services.  However, deep list or deep job analysis does require Professional Services time as this process is extremely time consuming.

Hopefully, with all of the above information, you better understand what’s involved in missing email deliveries.  If you have questions or comments, we are always interested in hearing from you… so, please feel free to comment.