Client: Thunderbird 128.2.3esr (64-bit) - Windows 10 Server: Apache James 3.8.1 I have an internal email server with a self signed certificate. IMAP connections fail with a certificate error. SMTP connections succeed. This occurs on two instances of Thunderbird on separate windows PCs. This used to work OK, but stopped working after a server restart. The thunderbird log shows the following/ '''IMAP:''' 17:47:09.211 mailnews.imap.48: Connecting to avocet3:993 5 ImapClient.sys.mjs:111:20 17:47:09.261 mailnews.imap.50: Connected 5 ImapClient.sys.mjs:862:18 '''17:47:14.277 mailnews.imap.48: SecurityError: a SecurityCertificate error occurred ImapClient.sys.mjs:914:18 17:47:14.277 mailnews.imap.48: Connection closed. ImapClient.sys.mjs:944:18 17:47:14.278 mailnews.imap.48: SecurityError info: SSL_ERROR_BAD_CERT_DOMAIN ImapClient.sys.mjs:924:20 17:47:14.279 mailnews.imap.48: SecurityError cert chain: avocet3; serial# 00:E1:B6:E6:FF:22:51:38:34 ImapClient.sys.mjs:929:22''' 17:47:14.280 mailnews.imap.48: C: 40 LOGOUT ImapClient.sys.mjs:962:20 17:47:14.280 mailnews.imap.49: C: 95 LOGOUT ImapClient.sys.mjs:962:20 17:47:14.280 mailnews.imap.50: C: 96 LOGOUT ImapClient.sys.mjs:962:20 17:47:14.281 mailnews.imap.51: C: 24 LOGOUT ImapClient.sys.mjs:962:20 17:47:14.281 mailnews.imap.52: C: 25 LOGOUT ImapClient.sys.mjs:962:20 17:47:14.282 mailnews.imap.48: Done with status=2153394164 ImapClient.sys.mjs:1851:18 17:47:14.291 Component returned failure code: 0x805a2ff4 [nsIUrlListener.OnStopRunningUrl] ImapClient.sys.mjs:1853 '''SMTP:''' 17:50:54.458 mailnews.smtp: Sending message <23ec25c1-4bb8-4351-a52b-a1e3738c6d50@ponder-stibbons.com> OutgoingServerService.sys.mjs:89:18 17:50:54.466 mailnews.smtp: Connecting to smtp://avocet3:465 SmtpClient.sys.mjs:134:19 17:50:54.523 mailnews.smtp: Connected SmtpClient.sys.mjs:431:17 17:50:59.564 mailnews.smtp: S: 220 avocet3 JAMES SMTP Server Server (JAMES SMTP Server ) ready SmtpClient.sys.mjs:454:17 17:50:59.567 mailnews.smtp: C: EHLO [192.168.178.66] SmtpClient.sys.mjs:679:19 17:50:59.592 mailnews.smtp: S: 250-avocet3 Hello [192.168.178.66] [192.168.178.66]) 250-AUTH LOGIN PLAIN 250-AUTH=LOGIN PLAIN 250-PIPELINING 250-ENHANCEDSTATUSCODES 250 8BITMIME SmtpClient.sys.mjs:454:17 17:50:59.595 mailnews.smtp: Possible auth methods: PLAIN,LOGIN SmtpClient.sys.mjs:961:17 17:50:59.596 mailnews.smtp: Current auth method: PLAIN SmtpClient.sys.mjs:719:17 17:50:59.597 mailnews.smtp: Authentication via AUTH PLAIN SmtpClient.sys.mjs:734:21 17:50:59.607 mailnews.smtp: C: Logging suppressed (it probably contained auth information) SmtpClient.sys.mjs:675:19 17:50:59.643 mailnews.smtp: S: 235 Authentication Successful SmtpClient.sys.mjs:454:17 17:50:59.652 mailnews.smtp: Authentication successful. SmtpClient.sys.mjs:1191:17 17:50:59.653 mailnews.smtp: C: MAIL FROM:<jim@ponder-stibbons.com> BODY=8BITMIME SmtpClient.sys.mjs:679:19 17:50:59.668 mailnews.smtp: S: 250 2.1.0 Sender <jim@ponder-stibbons.com> OK SmtpClient.sys.mjs:454:17 17:50:59.669 mailnews.smtp: MAIL FROM successful, proceeding with 1 recipients SmtpClient.sys.mjs:1226:17 17:50:59.669 mailnews.smtp: Adding recipient... SmtpClient.sys.mjs:1231:17 17:50:59.669 mailnews.smtp: C: RCPT TO:<smitjb0809@gmail.com> SmtpClient.sys.mjs:679:19 17:50:59.716 mailnews.smtp: S: 250 2.1.5 Recipient <smitjb0809@gmail.com> OK SmtpClient.sys.mjs:454:17 17:50:59.719 mailnews.smtp: Total RCPTs during this connection: 1 SmtpClient.sys.mjs:1293:19 17:50:59.720 mailnews.smtp: RCPT TO done. Proceeding with payload. SmtpClient.sys.mjs:1296:19 17:50:59.721 mailnews.smtp: C: DATA SmtpClient.sys.mjs:679:19 17:50:59.743 mailnews.smtp: S: 354 Ok Send data ending with <CRLF>.<CRLF> SmtpClient.sys.mjs:454:17 17:50:59.751 mailnews.smtp: Sending 397 bytes of payload SmtpClient.sys.mjs:647:17 17:50:59.771 mailnews.smtp: S: 250 2.6.0 Message received SmtpClient.sys.mjs:454:17 17:50:59.771 mailnews.smtp: Message sent successfully. SmtpClient.sys.mjs:1355:21 17:50:59.772 mailnews.smtp: Start 5 second QUIT timer