Tags can be synced over several computers with the same IMAP account if the mail server supports keywords:

http://kb.mozillazine.org/Tags#IMAP

If keywords aren't supported, use separate folders to store messages, corresponding to the tags, and subscribe the folders on all devices.

hello, I have a similar issue with Thunderbird.

Actually, I am using same email accounts on 3 different computers. I have deleted all tags, and created my own tags on all 3 computers. same colors, same orders, same names...

2 computers are syncing tags. i.e. when I put tags on 1 computer, I see it very fast on another computer as well. unfortunately, the 3rd computer, is not seeing any tags. and if I apply tags from this last computer, the other 2 computers are not seeing it as well.

looks like syncing is being blocked somehow.

any ideas? where to look?

Is the 3rd computer set up as POP or IMAP? It must be the latter for syncing.

I am having the same issue. 5 computers, 5 color tags, all the same on all computers. Most have 2 of the same email accounts. For 1 email account the tags are syncing across all computers properly. For the other email account, the tags are NOT syncing. I have looked everywhere for a setting that is different, anything, but to no avail. Does anyone have any insight???

Keep in mind that tags don't sync across all devices for all mail providers, and this is independent of the mail client, e.g. TB.