Dear Thunderbird Support Team,
I am writing to report an issue with custom message tags in Thunderbird that started occurring around September 28, 2026 (likely following … (read more)
Dear Thunderbird Support Team,
I am writing to report an issue with custom message tags in Thunderbird that started occurring around September 28, 2026 (likely following a recent update).
Issue Description:
The problem applies to all folders (Inbox, Sent, custom subfolders, etc.) and is strictly isolated to user-created (custom) tags.
When I apply a custom tag to any email, the tag visually attaches to the message. However, as soon as I switch to another folder in the folder pane and then return to the original folder, the custom tag disappears completely.
Key Observations:
No Relation to Filters: This issue happens with regular emails in any folder, with no filters involved.
Custom Tags vs. Default Tags: This affects only custom tags created by the user. Default built-in tags (e.g., Important, Work, To Do) save correctly and persist after switching folders.
Timeline: All custom tags assigned before September 28, 2026, are still preserved correctly on older emails. The issue affects any new attempt to set a custom tag after this date.
Steps to Reproduce:
Select any email in any folder.
Apply a user-created (custom) tag to the email.
Observe that the tag is visually assigned.
Click on any other folder to switch views.
Return to the original folder — the applied custom tag is gone.
Could you please assist in resolving this issue or suggest a fix/workaround? Custom tags are essential for our daily email management.
Thank you for your help and support.
Best regards,
Ihor Hirnyi
E-mail: ig@zrn.com.ua
