Immediate and Delayed Bounced Email Events

Email bounces that occur when you send out email from any email software sending program can occur in two different way:

An Error During Sending - During sending, if your SMTP server deems a certain email address as permanently undeliverable, then your SMTP server will return a 500-series error code which tells Campaign Enterprise or Email Marketing Director to hard bounce that email immediately. These kind of immediate hard bounces usually only occur for two reasons: The email address was malformed or the mail system you are sending through has "authority" over the domain of the email being sent and can just right on the spot if the email address is good or not. We see this happen a lot with Exchange servers where you both you the Exchange Server for receiving and sending emails. If your company domain is hosted on the Exchange server then the SMTP server of the Exchange server will only allow valid email addresses to be sent with those domains.

Returned Email - This is the most common way bounces are recorded because most of the time your SMTP server does not have the immediate authority to say whether or not an email address is valid. In this scenario your SMTP server simply relays the email message you sent to the SMTP server that has authority for the domain (from the MX record). When your SMTP server is talking to the target SMTP server, the target SMTP server might say "that email box does not exist" which is a 500 series error. This triggers your SMTP server to send the email back to you (or your bounce account). This can take seconds to hours to happen.

So, overall, bounces are somewhat difficult to deal with since they may happen from several different source, and since there is no standard for the formatting of bounces, it become the task of our software to decipher a bounced email which may have all or just part of the original message. In the next article, we will discuss the different ways to deal with the returned emails.

Microsoft Exchange Server Sending Speed

Many email professionals use Microsoft's Exchange server to send out their emails from Campaign Enterprise or Email Marketing director. The number one complaint we get is usually that it is very slow even though they are on "a super fast system on a fast internet connection." By default, Exchange Server is not setup to be a mass email system. In fact, they have created many settings by default to stop email from being accepted at a rapid pace. Depending on your Exchange Server version, there are settings you can look at to stop this throttling. A prominent term used is "tarpitting." Now the subject of tarpitting mainly concerns a set of parameters you can set in your Exchange Server so that it will accept emails at a rapid pace. Because of all the version of Exchange Server out there, and with them trying to deal with the SPAM issue through time, there are different settings for each of these versions which we cannot cover, but hopefully this article will uncover a nagging problem you might be having. Now keep in mind, many Exchange Server administrators may not even know what you are talking about because it is a rare occurrence and they probably have not encounter it before, so you may have to prime the pump with some Google service on "Exchange Server SMTP slowness" and show them some of the settings they will have to deal with.

Bounces - The Wild West of the Internet

Bounced email is a subject that comes up very often in our tech support department. In this blog we will try to define all the aspects of email bounced and how to deal with them. But first we need a reason...

Dealing with bounced emails is very important. Many times bounced emails are just ignored because it does not "cost" anything to just keep sending to the same email addresses. The problem is that many mail providers like AOL, Hotmail, Gmail are all sensitive to emails sent to them that do not exist. For instance, if you are sending 1000 emails to AOL addresses and hundreds of them does not exist, AOL will consider you a spammer because you are not a "good citizen" and will at some point not allow your SMTP server to send ANY more email to them. When you do this to all the major email providers all the time you can see why many of the emails you send out will just not make it to the REAL end users. So overall, you need to deal with bounces to keep your reputation clean.

As explained in a previous blog, bounces can happen immediately or delayed. Immediate bounces happen when your SMTP server rejects the email the instant it is submitted. These records can be marked as "bad" in Campaign Enterprise and then you would filter these addresses on the next send or just delete them completely. The delayed bounced emails are the tricky ones. Here is how a bounce is generated:

1. You send an email using your SMTP server

2. You SMTP server verifies the format of the email address and accepts the email message into it's queue

3. Sometime later, your SMTP server looks up the MX record for the domain of the email address (like AOL.COM)

4. If the domain does not exist, then your SMTP server sends a bounced email to your bounced email account

5. If the domain exists, your SMTP server now contacts the destination SMTP server

6. The email message is submitted to the destination SMTP server

7. The destination SMTP can immediately reject the email message, and if it does, then your SMTP server sends a bounced email to your bounced email account.

8. If the destination SMTP does accept your email message, it can then reject it later if it finds a problem. In that case, the destination email address will send a bounce email to your bounced email account.

So, from all of this, you can see that the actual bounced email you receive can come from many different sources. The "Wild West" reference in the title refers to this process and also to the actual contents of the bounced email: There are no rules about the content. This makes if very difficult for us. To properly record a bounce we need to know two major things: The original email address we sent to, and what the error was. Sounds easy? Nope. With all the email systems throughout the world, there are that many different bounced email formats, and they change, all the time. So harvesting information from bounced emails is truly an "art" and is a good reason to keep updating your Campaign Enterprise product because we strive to keep up with all these formats.

In tomorrow's blog, we will discuss the differences between "soft" and "hard" bounces because it is a big subject in how to deal with these.