Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have an HTML signature with a web-based image. The image changes about once a month, but Thunderbird keeps using an old image. I believe it's being cached somewhere.

Any ideas on how to ensure the image is dynamically fetched every time?

share|improve this question

On the server side:

Add an adequate Cache-Control header in the server's response for the image. E.g. Cache-Control: max-age=0 - On Apache this could be achieved through a .htaccess file using the Header directive. Please add details about the used web server to your question if you need further information on how to configure this.

On the client side:

Set browser.cache.check_doc_frequency to 1 in Tools –> Options –> Advanced –> General -> Config Editor...

Either way will work to prevent Thunderbird from using the image without checking the cache freshness, but you probably want to use the server side way to make sure your recipients see your signature correctly.

share|improve this answer
The client side worked well. I just needed to restart tb – duduklein Nov 27 '14 at 11:10

You can manually purge Thunderbird's image cache by deleting the TB cache directory:

  • close TB
  • navigate to your TB profile folder...
    • on Windows:
    • on Mac OS X:
    • Attention: In both cases those folders are hidden by default!
  • delete or rename the sub-folder Cache in your profile
  • restart TB
share|improve this answer

How about generating a new filename each time, and dynamically updating your sig file as well? More work than just replacing the image, but less work possibly than changing the server header response.

share|improve this answer

Thunderbird now ships with the option to clear the cache. Go to Tools -> Clear recent history…

share|improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .