Are you one of those marketers that faithfully remove bounced email addresses from your members list? OR are you that marketer than just cannot let go of that bounced address, adding it back into your list for future mailings? After all, most bounced emails are the result of full mailboxes right? Well actually no, most aren’t. A full mailbox is easily identified by most ESP’s bounce reports. Automation tools, like the ones built into (Lyris) Aurea ListManager, handles those types of bounces for you, in fact (Lyris) Aurea ListManager™ by default will handle all the error mail.
If your ESP does not have full bounce automation, a bounce report in hand will allow you to manage your bounces manually, so you can maintain that great response rate you get after each campaign. This is easy to do once you know the different type of email bounces and bounce categories, as follows:
The Bounce Categories
We can categorize email two ways: synchronous or asynchronous. Synchronous bounces are instantaneous as the failed delivery attempt is bounced back immediately. An asynchronous bounce is a message that, after a period of time, is returned after the message was sent out.
The way the message is intercepted will determine the speed in which it is returned in bounce state.
- An email sent to an invalid address for example, will be terminated when the receiving server identifies the address as invalid, the connection is cut and the email is returned: a synchronous bounce.
- An asynchronous email bounce occurs when the receiving server attempts to process the invalid email, acknowledges the message and continues to attempt to deliver it until the delivery fails. For example, if a mail server accepts a message and later determines the user does not exist that recorded bounce is asynchronous.
Once an email falls in one of these two categories: synchronous or asynchronous, it is further assigned a bounce type, as identified in the return email header.
The Soft Bounce
A soft bounce also known as transient failure is email that has bounced back to the sender, undelivered after it has been accepted by the recipient’s mail server. This is usually a temporary condition with an expectation of clearing up in the future. However, it is good practice to monitor soft bounces and remove them from your list when they bounce a certain number of times in a row. Advanced email tools automatically handle this process.
For example, our hosted software by default, will try to send a message three times – the initial send, and two retries. If a mail server reports that an address is permanently non-deliverable, ListManager will only attempt to deliver it once for that mailing. This is known as a permanent failure or hard bounce. Messages that are undelivered for other reasons, like a full mail box, are known as a transient failure or soft bounce. In that instance if an address is undeliverable for the initial send, even with all the retries it’s considered to have only bounced once.
Soft Bounces may occur when
- An Email is returned undelivered because the receiver’s mailbox is full at that time.
- An Email Message Size is too large to be delivered.
- Auto responders, such as a vacation or out of the office message may be incorrectly reported as a bounce.
- The connection to the sending or receiving server timed-out.
- The connection was refused.
- Network issues.
The Hard Bounce
All things not being equal a soft bounce on one sever maybe interpreted as a hard bounce on another server. A hard bounce is normally perceived as a long-term or permanent condition that generally is not expected to clear up any time soon. It is good practice to remove hard bounces when they occur. However, you might want to develop an internal policy to remove the address after a few consecutive bounces, as hard bounces may clear up: e.i. temporary system fault or a blacklisted domain.
Hard Bounces may occur when
- The recipient address is misspelled.
- The user doesn’t exist
- Your domain is blacklisted
Some ESP’s such as Dundee Internet, offers a more granular bounce grouping rather than just a “Hard and Soft Bounce” report, accentuated with a uniquely colorful graph for easy evaluation.
Next time you send your campaign, review your bounce report. It should give you enough details to distinguish which bounces came from where and why. Manage your bounces to maintain that great response rate you work so hard to achieve. It’s well worth it. If your ESP isn’t giving you the detail you need, drop a note to firstname.lastname@example.org I’ll send you a sample report.