By: Chris Lewis
When you send out an email and something goes wrong with it being delivered it is usually returned to you or "bounced". Bounced emails can happen for various reasons, some of them being permanent and some of them being temporary.
Hard Bounces - Hard bounces happen when any of the SMTP servers down that the email address you used to send will just never work. One of the first reasons an email will not reach it's destination is that the domain name does not exist. The second reason is that the mailbox on the mail server for that domain just does not exist. Hard bounces are usually characterized by a 500-series error. When an email is returned with a 500 series error inside, Campaign Enterprise and Email Marketing Director will categorize these as hard bounces. Usually when a hard bounce like this occurs, you mark a hard bounce field in the corresponding database record, and then when you send using that list again you filter out any email records that have this hard bounce field marked. Since it is a permanent failure, there is no reason to try sending to that address again. Aside from other information you want to keep in that record, the email address is virtually useless.
Soft Bounces - When a returned email not a 500-series return code, it is assumed to be a temporary or soft bounce. These types of bounces usually mean the domain is good and the email box is valid but for some reason the email server is not accepting any emails for this address at the present time. The reasons can range from the mail box is full, the server is too busy, or the person has marked his account as being on holiday. In the case of soft bounces, it is ok to try again the next time you send using that list. There will come a time though when maybe too many soft bounces really means a hard bounce...where an email box is always full (maybe not in use). In this case, you many not want to filter soft bounces out until a certain point, say, you get 20 soft bounces for that email address. In that case, you can filter the email list to exclude any records that have over 20 soft bounces. Now this is very arbitrary so you will have to set the number of times a record can soft bounce before you remove it from the list. Many times, sending emails to these addresses over and over is ok because the destination mail server does see the email box as valid, just not reachable, and that is not a bad mark on you.
So, for many, they just worry about hard bounces because those are the ones they can get in trouble with concerning the big mail providers. I would recommend just ignoring the soft bounce recording but it is up to your companies conventions.
BTW: Hotmail just got transformed to a new mail service called OUTLOOK.COM. We will be following this change to see how it affects our customer's deliver ability so check back over the next few weeks.
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.