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.