Virtual Mailer Documentation
Email Bounce Suppression
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Email Bounce Suppression

How Virtual Mailer detects bounced addresses, suppresses future sends to invalid emails, and shows that status to users in Contacts, Mailing Lists, and the Contact Editor.

Purpose

What Bounce Suppression Does

Email bounce suppression helps you avoid repeated delivery failures by preventing future campaign sends to email addresses that have already produced a permanent bounce.

Receive

Returned bounce messages are sent to the bounce mailbox configured on the Mail Account.

Classify

Virtual Mailer records the bounce event, classifies the response, and applies additional targeted rules for known invalid-recipient patterns.

Suppress

Permanent bounce addresses are excluded from future sends and shown in the user interface as suppressed.

Suppression is tied to the current email address. It is not a permanent mark on the contact record itself.
Setup

Where It Is Configured

Bounce suppression is driven by the sending Mail Account. Each sending account can have its own return-path address and bounce mailbox settings.

  1. Open Mail Accounts.
  2. Edit the account used to send the campaign.
  3. Open the account's advanced settings.
  4. Complete the Bounce Processing section.
  5. Save the account after the mailbox connection details are entered.
Setting Why It Matters
Return-Path Address Defines where returned bounce mail should go.
Protocol Tells Virtual Mailer whether to connect by IMAP or POP3.
Server, Port, and SSL Provide the technical connection details for the bounce mailbox.
User and Password Allow Virtual Mailer to sign in and retrieve bounce messages.
If bounce processing is not configured for a Mail Account, returned bounce messages normally go back to the sender address instead of being collected and processed by the dedicated bounce-sync feature.
Sync Process

How Suppression Gets Applied

  1. A campaign is sent using a Mail Account with bounce processing configured.
  2. Returned bounces arrive in the configured bounce mailbox.
  3. The operator opens the Campaign and clicks Sync Bounces.
  4. Virtual Mailer reads the mailbox, records the bounce history, and identifies the affected recipient email.
  5. The application evaluates both the parsed bounce type and known invalid-recipient patterns in the returned message.
  6. If the response indicates the address should no longer be mailed, that email address becomes suppressed for future sends.
If bounce messages have not been synchronized yet, the suppression status will not appear yet in the application.
Mailbox Choice

Using a Shared Mailbox for Bounce Processing

Virtual Mailer can read a mailbox that contains mixed content, including normal mail, unrelated bounced mail, and bounces generated from campaigns sent by other systems. This is supported, but it is not the recommended setup.

What Virtual Mailer Does

  • Messages that are not recognized as bounce messages are left alone.
  • Messages that are recognized as bounce messages are recorded in bounce history, even if they cannot be matched back to a Virtual Mailer sent message.
  • If Leave processed messages on server is turned off, recognized bounce messages are removed after processing.

Why a Shared Mailbox Can Be Risky

  • Unrelated bounced mail in the same mailbox can still be recorded.
  • If the bounced address matches one of your contacts, that address can still become suppressed.
  • If processed messages are not left on the server, unrelated bounce messages in that mailbox can also be removed.
Best practice: use a dedicated mailbox for bounce returns for each sending account or sending workflow. This keeps bounce history clean, reduces the chance of unrelated suppressions, and avoids deleting bounce mail that belongs to some other system.
Suppression Rules

Which Bounces Suppress Future Sending By Default

Usually Suppressed

  • MailBee hard bounces
  • Recipient address changed
  • 5.4.1 Recipient address rejected: Access denied
  • 5.1.1 invalid-recipient failures
  • 5.1.10 RecipientNotFound
  • Category: hard in the bounce body
  • no such user, recipient not found, or does not exist

Usually Logged Only

  • 5.2.2 mailbox full
  • Quota exceeded conditions
  • Temporary server problem
  • Retry-later or deferred conditions
  • Other soft or temporary bounce conditions that do not identify the address as invalid
Virtual Mailer does not suppress every soft bounce by default. The goal is to suppress addresses that appear invalid while leaving temporary delivery problems available for later retry.
How Virtual Mailer Decides

Parsed Type Plus Targeted Reasoning

Virtual Mailer starts with the parsed bounce type returned by the bounce-processing engine. It then applies a small set of targeted default rules for known invalid-recipient patterns.

  • A generic permanent-looking status code by itself is not enough to suppress an address.
  • A specific invalid-recipient pattern such as 5.4.1 Recipient address rejected: Access denied is treated as suppressing by default.
  • Temporary conditions such as mailbox-full responses remain logged without suppressing the address.
This approach helps protect sender reputation without turning every soft delivery problem into a permanent suppression.
UI Indicators

Where Users See Suppressed Status

Screen Indicator Meaning
Contacts Suppressed column in the contacts grid The contact's current email address matches a suppressed address in bounce history.
Mailing Lists Suppressed count in the main Mailing Lists grid and Suppressed column in the mailing list members grid The list contains one or more members whose current email addresses should not be mailed until corrected.
Contact Editor A visible warning notice The contact's current email address is still suppressed.
Correction

What Happens When the Email Address Is Changed

The suppression indicator is based on the contact's current email address.

  1. If the contact still has the bounced email address, the record shows as suppressed.
  2. If the contact is updated to a new valid email address, the suppressed indicator disappears.
  3. The original bounce event still remains in history for the old failed address.
This makes the indicator useful as a cleanup signal. It tells the user the current email needs attention, but it does not permanently lock the contact record.
Recommended Use

Day-to-Day Workflow

  1. Configure bounce processing for each sending account you actively use.
  2. Use a dedicated mailbox for bounce returns whenever possible.
  3. Run Sync Bounces after campaigns have had time to generate returned mail.
  4. Review Contacts and Mailing Lists for records marked Suppressed.
  5. Correct addresses when you have an updated valid email for the same contact.
  6. Leave the record suppressed when the address is no longer valid.
Troubleshooting

If the Indicator Does Not Appear

  • Verify that the Mail Account bounce settings are complete and correct.
  • Confirm that returned bounce mail is reaching the configured mailbox.
  • Run Sync Bounces after the campaign has generated returned mail.
  • Check whether the message was a temporary response such as mailbox full rather than an invalid-recipient response.
  • Remember that only targeted invalid-recipient patterns are suppressed by default. Other soft bounces are still recorded for review.
  • Remember that if the contact email has already been corrected, the contact will no longer show as suppressed.