I recently noticed that version of the Thunderbird is not same on my laptop and on my iMac. Thunderbird verson on my iMac was 13.x while on my laptop it was 15.x. It looked suspicious and I changed repository location on my iMac to point to the main repository instead of Maltese mirror. It turned out that 422 packages should be updated!
Is there a way to make sure that mirror is updated?