Thunderbird retains access to old DNS entries, how to purge them?

pbhj

10/8/23, 3:51 PM

So, I have a pihole and I'd blocked an address in the pihole (www.tm.ak.prd.aadg.trafficmanager_net [address munged on purpose]) which caused login to login.microsoftonline.com from a browser to fail, and also caused Thunderbird to fail to login to outlook.office365.com to use IMAP. I've removed that address from my pihole blacklist and now nslookup/mtr return expected results (whilst they didn't before), I can login from my browser (eg Firefox) ... but thunderbird still fails and reports that the server may be down (after saying the password is wrong and after the fifth time of me telling it to retry; the pw is right, and as I said I can login from my browser using that password on the same machine).

So, it seems like thunderbird (version 102.3.2) has some sort of DNS cache, which has survived me flushing DNS on the pihole and rebooting the local machine (which is using systemd-resolved). As I said, domain resolution all works with the browser now, whilst it didn't before (due to the blacklist of the domaing above).

How is Thunderbird retaining a stale DNS resolution and how can I refresh it? Thanks.

FWIW I'm hoping that the cache will expire/timeout, and access will return, but would like a process to force--what I assume is--Thunderbirds hidden caching to be purged if that's possible.

278

0 + 4

thunderbird

networking

dns

22.04

exore

10/13/23, 5:30 AM

weird indeed. Can you make sure tb is actually trying or not trying to connect to the machine ? so close TB, then in a terminal run `sudo tcpdump "(port 143 or port 993) and tcp[tcpflags] & (tcp-syn|tcp-fin) != 0"`, and start tb while tcpdump is running. You should see in the terminal all the IMAP opening and closing connections.

Simon Sudler

10/14/23, 7:49 AM

Just to be sure: Please execute the following command and post the output (if it fails) `openssl s_client -host outlook.office365.com -port 993 < /dev/null`

pbhj

10/15/23, 2:42 PM

Thanks for the tips, the domain did expire from cache within a couple of days (not sure when exactly). So I'm trying to test it now, but of course it's "cached" (or some other way) the working domain resolution so I'll need to wait for Thunderbird to notice that the domain is blacklisted in DNS (on the pihole) before I can test. Will update in the next few days.

pbhj

10/21/23, 7:51 AM

I can't reasonably reproduce this behaviour. Thank you for your useful suggestions.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Thunderbird retains access to old DNS entries, how to purge them?

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.