Troubleshooting Email Deliverability – Postmaster Messages

When sending bulk messages from the Boldem platform, you may receive emails from the address postmaster@example.cz with information about undelivered emails. These messages can take various forms and usually contain technical details about why an email could not be delivered to a specific recipient. For example:

Why is this happening?

Some recipients’ email servers may be set to accept an email immediately but only process its final deliverability later. In the first phase, the Boldem sending platform therefore receives information about a successful delivery, and the email’s status in the system is marked as Delivered. However, in a later phase the recipient’s server may decide that the email cannot be delivered, for various reasons, such as:

• nonexistent email address,
• recipient’s inbox full,
• Quarantining an email because feedback marked it as spam, a phishing attempt, or infected with a virus.

In these cases the recipient’s server does not send immediate feedback to Boldem; instead it sends a DSN (Delivery Status Notification) to the sender’s email address. This behavior may cause Boldem’s statistics to not always accurately reflect the actual number of delivered or bounced emails.

Issue resolution – recommended setting

If you want these delivery-failure details to be automatically synced to Boldem, additional configuration is required:

Dispatch from a subdomain and MX record setup

We recommend sending bulk messages from a subdomain dedicated solely to this purpose, e.g. info@novinky.example.cz, instead of the main domain novinky@example.cz. This helps separate regular company communication from marketing deliveries, improving overall email deliverability and protecting the reputation of the main domain.

You also need the emails sent to the subdomain to be processed in Boldem. The setup procedure is as follows:

1. Create a subdomain with any name you choose at your hosting provider, e.g., novinky.example.cz.
2. Create an MX record for the subdomain with priority 1, the default TTL (e.g. 3600), and the target address bounce.boldem.cz.
3. Enter the subdomain in the Domain settings section of your Boldem account. Follow the instructions in the chapter Sending domain verification.
4. Make sure all DNSThe Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resource... records are set up correctly and verify the domain in the Boldem app.

This setting ensures DSN messages are processed by Boldem, allowing undelivered emails to be correctly marked directly in the app.

Reply-to email address settings

If your clients regularly reply to your bulk emails and you want to receive those replies, enter the Reply-to email address in the Message sender step when setting up a campaign in Boldem. For the Sender email, choose the mailbox on the subdomain as described above. For example:

Manual processing of undelivered messages

If for some reason you don’t want to route your MX record to Boldem, you can set up your own email mailbox on a subdomain and manually process all incoming DSN messages. When you receive a delivery failure notification, it’s important to:

• Assess the type of delivery failure and, for permanent issues, unsubscribe nonexistent contacts in Boldem from your bulk messages to prevent repeatedly sending emails to invalid addresses.

Preventing further dispatches to full or nonfunctional mailboxes is an important step that protects the reputation of your domain and your sending IP addresses, which is critical for deliverability.

More tips to improve deliverability

• Monitor feedback: Track deliverability statistics and focus on any issues with specific domains or mailboxes.
• Avoid being marked as SPAM: Make sure your content isn’t perceived as unsolicited mail. This includes proper content personalization, correct email formatting, and following the rules for bulk deliveries.
• Monitor messages marked as SPAM by recipients and evaluate related information using the Seznam Feedback loop and Google Postmaster services. We strongly recommend setting up these services, especially for medium and large companies. If degraded deliverability is detected, the Boldem service provider reserves the right to require their mandatory setup.
• Contact testing and validation: Regularly update your contact database and test their validity to minimize the risk of dispatching to invalid email addresses.

This ensures emails are delivered correctly and reduces the chance of receiving messages from postmaster@example.cz about delivery failures.