This function attempts to detect emails which are returned as "undeliverable". About a half of the bounce-mails come from your own mail-server, the other half from the recipient's mail-servers. Some bounce-mails will return immediately, others may last several days. This also depends upon how the mail-servers are configured. Some servers repeat to deliver the mail for several days, in case of errors.
Select "Bounce detection" usually in combination with "Add sender to exclusion database" for the Action. By this, all permanently undeliverable email addresses will be added to the BulkMailer exclusion list.
Unfortunately, very most of the bounce-mails don't follow a standard. The program looks up some distinct key-words within the bounce-mail, and then finds an email address close to it. The program tries to distinguish between Hard-Bounces and Soft-Bounces. Hard-Bounnces are addresses, which are permanently undeliverable, such as "Unknown Host". Soft-Bounnces are temporary undeliverable addresses, such as "Out Of Quota". Only Hard-Bounces are excluded from further sending by the bounce-management.
For the reason, that bounce-mails are not standarized, the detection cannot be 100%. In practice you should achieve a very satisfying rate of far above 90%. When too many emails could not be detected successfully, you could extend the key-words list in the file "bounce.cfg", which you can find in the BulkMailer program directory.
Today, many mail-servers count your tries to deliver invalid addresses. When trying too often, your mails could be classified as SPAM, because a human wouldn't do that. So it's worth to get rid of undeliverable addresses as soon as possible in order to maintain a clean list.
Condition: Search string
In most cases, a simple search string is sufficient for the condition. It can have one of the following scopes:
- in the sender address
- in the subject line
- in the entire message text.
The condition is fulfilled when the search string appears at least once. The comparison is case-insensitive.
If you leave the field for the Search string empty, then this condition is always fulfilled. This is by default used with the very last action, to catch all other mails, which have not been processed by any other action.
You can generate complex character sequence comparisons with the help of what is known as a Regular Expressions. This involves a powerful and standardized syntax for Pattern-Matching which cannot be described here in complete detail.
Testing Regular Expressions
Because the generation of Regular Expressions is always somewhat tricky, the program offers a test function to make this task easier. Once you have entered a Regular Expression, enter a comparison term in the field "Test" and click on "Test RegExpr.".