Thunderbird

Permanently Block a Sender in Thunderbird: Emails & Domains

By Admin

Updated: March 13, 2026 ~ 4 Minutes Reading

Table of Contents

You can block messages from a specific sender or a particular domain in Thunderbird. Even though Thunderbird does not have a Block Sender button, you can get rid of emails from unwanted senders using Message Filters.

What Happens When You Block a Sender in Thunderbird?

When you prohibit an email address or domain in Thunderbird from sending messages, you directly move emails from that sender to the Trash or Deleted folder, and it will be completely removed from the account based on the retention policy of the folder.

Moving an email contact to a blocked folder does not automatically stop the email server from receiving messages from that account. However, after an IMAP sync is completed, it will be removed from the email server as well.

Note: There is no set limit on how many email addresses you can block in Thunderbird.

Restrict an Email Address in Thunderbird -Using Message Filters

  1. Open an email message from the sender in Thunderbird.
  2. Click on the sender’s email address on the top left.
  3. Choose the Create Filter From option.
    Thunderbird interface showing the create filter option to block a sender email address
  4. Name the filter as Blocked Contacts.
  5. Ensure the Getting New Mail box is checked.
  6. Select the Match Any of the Following checkbox.
  7. Choose Delete Message from the Perform these actions dropdown.
    Multiple filter rules setting to setup block contact list in Thunderbird like Getting new mail, Perform action etc.
  8. Press Ok to confirm and then click Run Now.

How to Add a Sender to the Block Contacts List?

You do not need to create a new message filter every time to block a sender in Thunderbird. Here is how you can manually add an email address to the Blocked list.

  1. In Thunderbird, go to Tools >> Open Message Filters.
  2. Select the Blocked filter and press Edit.
  3. Click on the (+) plus icon.
  4. Enter the email address of the sender to be blocked in Thunderbird.
    How to add a new sender in the Thunderbird block list
  5. Press Ok and then Run Now.

How to Block Emails from a Domain in Thunderbird?

You can add multiple block email addresses from a domain to help you avoid all marketing-related or unwanted emails from a company.

For Better Understanding: In an email address, the name@abcd.com name in the username and abcd is the domain name.

  1. Go to Menu >>Tools >> Open Message Filters in Thunderbird.
  2. Open the block contacts filter and press Edit.
  3. Click on (+) plus to add a new attribute.
  4. From the “Is” dropdown, select “ends with”.
  5. Enter the name of the domain.
    Thunderbird filter rules settings to block an entire domain in Thunderbird
  6. Hit Ok >> Run Now.

Steps to Unblock a Contact in Thunderbird

It is very simple and quick to unblock a sender from the Thunderbird block list.

  1. Go to the Menu >> Tools >> Message Filters.
  2. Select and Edit the blocked contact list.
  3. Click on the minus (-) button in front of the sender you want to unblock in Thunderbird.
    minus (-) button in Thunderbird filters to unblock a blocked sender in Thunderbird
  4. Press Ok and Run Now.

Important Recommendation

You can immediately get rid of the messages from the blocked sender by modifying the retention policy of the deleted folder. Once the IMAP sync gets completed, the messages will also not be visible in the webmail as well.

  1. Right-click on the Deleted Folder.
  2. Select the Properties Option >> Retention Policy.
  3. Choose the delete messages more than option.
  4. Set days to “0” and press Ok.
    retention policy setting to immediately delete all the emails from blocked sender in Thunderbird
  5. You will have to repeat for each account separately.

Please Note: Blocking a sender in Thunderbird is not a True block. You need to block the user from the webmail itself.

When Should You Block a Sender in Thunderbird? Reason

There can be a few reasons why a user may want to deny list an email address or domain in Thunderbird.

  • Repeatedly sending unwanted, spam, or marketing emails.
  • When better managing and decluttering Thunderbird mailboxes.
  • Avoid risk of hacks and phishing emails from malicious accounts.

Protect your Thunderbird Emails in a Better Way?

Use Thunderbird Backup Tool to back up your entire Thunderbird profile data with safety and in minimal downtime, all while ensuring a complete backup of contacts, calendars, and properties. A Free Trial version of the tool is available.

Read More: How to Restore Thunderbird Backup?

FAQs: Block Email Addresses in Thunderbird

Q1: Can I block an unwanted email sender?
Yes, you can do so with the message filters; however, there is no direct option to block a sender in Thunderbird.

Q2: Will the sender be notified if I block them in Thunderbird?
No, their messages won’t simply appear in your inbox after you block them.

Q3: How to block spam emails in Thunderbird?
Open Thunderbird, go to Menu >> Settings, then Privacy & Security. Search for spam settings and choose the Delete Them option from the “When marked as Spam section.”

Read More: Migrate Thunderbird to GoDaddy Workspace