The Bounce Addon

Note: We always recommend using a professional delivery service to send your marketing email and get the bounces correctly managed. We cannot grant the extension will be able to detect all kinds of bounces.

When a message is sent to an invalid or unreachable address, most of the time you’ll receive back a delivery error message as a response (it can take from a few seconds to appear to some hours or even days).

If correctly formatted, those error notification messages contain a set of data, called DSN (delivery status notification) with information about the kind of error (temporary, permanent, and so on).

More about bounces can be read here.

The Bounce addon tries to analyze those messages and find out if it has been generated by an email address in your database. If so, it will be marked as “bounced” and never contacted again.

What's inside

Use a dedicated mailbox!

You need to set up a new and dedicated mailbox to collect delivery error messages and let this extension manage them. Messages will be deleted from that mailbox once processed. Do not use your mailbox!

If you use Post SMTP as SMTP plugin

If you’re using the plugin Post SMTP, be aware that the “return path” set on the Newsletter plugin Main Settings is not respected.

If they can add an option to set that value (we should call it “Sender” but is a bit misleading for nontech humans), the return address needs to be set in that plugin.

How to configure this addon

The extension needs a dedicated mailbox (email address) where all the error messages are collected. The mailbox has to be accessible using the POP3 protocol.

To instruct externals to send error messages in the right mailbox, you need to configure the “return path” on Newsletter main settings with the email address you created in the previous step.

Hourly, Bounce opens the mailbox, reads all the messages, analyses them, and tries to detect if there are permanent errors reported. Extract the email address and mark it as bounced.

The POP3 configuration consists of a user name, password, hostname, and port (optional). Those parameters can be found in your provider’s instructions on how to configure a generic mail client.

If the mailbox can be accessed in secure mode (TLS, SSL), you can even select the security protocol to use but remember to set even the port (usually it differs from the standard 110 port number).

When it runs

The extension checks the mailbox every hour and processes up to 1000 messages (but this could change). For your convenience the last time the extension checked the mailbox and the next run are reported in the configuration panel.

Please note: if your blog has some resource-intensive background processes (for example you’re sending a newsletter to a big list) the bounce checks could be delayed or sometimes skipped.

With Gmail

If you use Gmail as a mailbox for your error delivery messages, the POP3 must be explicitly enabled since it’s not active by default. You can read more here.

Hard (permanent) and soft (transient) bounces

Reported errors can be “permanent” or “transient”. The first type means the email address cannot be contacted (for example it is not existing). The second type is a temporary problem, for example, a full mailbox, and could be solved in the future.

Usually, only permanent errors are processed and the related email marked as bounced, while transient errors are ignored. You can anyway configure the addon to process and consider bounced address even the once for which a transient error is reported.

Technically, permanent errors have a code with the format 5.X.X while transient errors have a code with format 4.X.X.

Even if the error code should help in classifying it in detail using the last two numbers (X.X), many email servers do not set them correctly, so the addon does not process the sub-error codes.

Test the configuration and errors

Once you configured it, you can test if the extension can connect to the POP3 server.

If the connection was fine, you have a success message with some debug info on top of the page.

The test extracts 10 messages, and analyzes them but is a “dry run”, the extracted emails are not processed nor the messages deleted. To check if messages are correctly retrieved try to send an email to your bounce dedicated mailbox.

If you got an error message

If you get connection timeout errors or generally an error message without more specific information, there are a few options:

  • the parameters you are using are not correct (for example the hostname, the password, the port, or protocol): double-check them with your provider; the most common error is to use the incorrect host or the username which does not always match the email address
  • If your provider has a firewall rule blocking the connection, ask them via their support tickets or try with different combinations of protocols and ports

Possible errors

  • If you can read in the error text “getaddrinfo failed” it means your server is not able to resolve the host you provided. Double-check it and if correct ask the provider to check the server to grant it can resolve the pop3 host.

Bounce checking timing

The extension reports the last time it checked for bounces and the next scheduled check. If you not it is not running at the correct timing, you have a problem with your WordPress scheduler. Check on top of the page for an error message and take the time to read this page about the WordPress scheduler.

Why is important to manage bounces

Trying to send messages to an invalid address, again and again, is considered spammy behavior and could be a reason to list your domain or your server on a blacklist. Detecting bounces lets you quickly react to invalid addresses and stop sending them more messages.