Bugzilla

Thanks, the log explains it. It appears that the imap provider, btinternet, is claiming the capability to support imap rfc for ID, https://tools.ietf.org/html/rfc2971 , but returns and error when tb sends the ID command.  Notice that ID is in in the returned capability string:

2019-08-08 08:38:07.216000 UTC - [4456:Unnamed thread 107FE190]: I/IMAP 1B4EF800:mail.btinternet.com:NA:CreateNewLineFromSocket: * CAPABILITY IMAP4rev1 UIDPLUS NAMESPACE QUOTA STARTTLS AUTH=PLAIN SORT SORT=DISPLAY MOVE **ID** THREAD=ORDEREDSUBJECT THREAD=REFERENCES THREAD=PARTICIPANTS X-THREAD X-FIRSTLINE CONDSTORE

When tb sends the ID command, btinternet responds with the error:

2019-08-08 08:38:07.512000 UTC - [4456:Unnamed thread 107FE6D0]: I/IMAP 1BF8E800:mail.btinternet.com:A:SendData: 4 ID ("name" "Thunderbird" "version" "60.8.0")
2019-08-08 08:38:07.528000 UTC - [4456:Unnamed thread 107FE6D0]: D/IMAP ReadNextLine [stream=1BF66880 nb=34 needmore=0]
2019-08-08 08:38:07.528000 UTC - [4456:Unnamed thread 107FE6D0]: I/IMAP 1BF8E800:mail.btinternet.com:A:CreateNewLineFromSocket: 4 BAD unrecognized IMAP4 command

Although you will see this error pop up, it really causes no harm since the ID command is really just for informational purposes and doesn't affect incoming email (and has no relation to outgoing email). Also, once connections are established, you won't see this again until connections are dropped due to inactivity which often occurs after about 1/2  an hour. Also, when you send an email and tb has been idle a while, you will see this when tb opens a new connection to the server to save the message to Sent folder.

Also, since sending ID is completely optional, other clients such as mobile mail apps may not even send it.

So either just ignore the error or notify btinternet of the problem and ask them to either remove ID from their capabilities or just return an empty OK response to the ID command which is acceptable per the rfc.

Thanks, the log explains it. It appears that the imap provider, btinternet, is claiming the capability to support imap rfc for ID, https://tools.ietf.org/html/rfc2971 , but returns an error when tb sends the ID command.  Notice that ID is in in the returned capability string:

2019-08-08 08:38:07.216000 UTC - [4456:Unnamed thread 107FE190]: I/IMAP 1B4EF800:mail.btinternet.com:NA:CreateNewLineFromSocket: * CAPABILITY IMAP4rev1 UIDPLUS NAMESPACE QUOTA STARTTLS AUTH=PLAIN SORT SORT=DISPLAY MOVE **ID** THREAD=ORDEREDSUBJECT THREAD=REFERENCES THREAD=PARTICIPANTS X-THREAD X-FIRSTLINE CONDSTORE

When tb sends the ID command, btinternet responds with the error:

2019-08-08 08:38:07.512000 UTC - [4456:Unnamed thread 107FE6D0]: I/IMAP 1BF8E800:mail.btinternet.com:A:SendData: 4 ID ("name" "Thunderbird" "version" "60.8.0")
2019-08-08 08:38:07.528000 UTC - [4456:Unnamed thread 107FE6D0]: D/IMAP ReadNextLine [stream=1BF66880 nb=34 needmore=0]
2019-08-08 08:38:07.528000 UTC - [4456:Unnamed thread 107FE6D0]: I/IMAP 1BF8E800:mail.btinternet.com:A:CreateNewLineFromSocket: 4 BAD unrecognized IMAP4 command

Although you will see this error pop up, it really causes no harm since the ID command is really just for informational purposes and doesn't affect incoming email (and has no relation to outgoing email). Also, once connections are established, you won't see this again until connections are dropped due to inactivity which often occurs after about 1/2  an hour. Also, when you send an email and tb has been idle a while, you will see this when tb opens a new connection to the server to save the message to Sent folder.

Since sending ID is completely optional, other clients such as mobile mail apps may not even send it.

So either just ignore the error or notify btinternet of the problem and ask them to either remove ID from their capabilities or just return an empty OK response to the ID command which is acceptable per the rfc.