Better support for Charter/Spectrum IMAP: Thunderbird will now detect Charter's IMAP service and send an additional IMAP select command to the server. Check the various preferences ending in "force_select" to see whether auto-detection has discovered this case.

FIXED:
In search folders spanning multiple base folders clicking on a message sometimes marked another message as read.
IMAP alerts have been corrected and now show the correct server name in case of connection problems.
POP alerts have been corrected and now indicate connection problems in case the configured POP server cannot be found.
Various security fixes.