Thanks for the update, Johnny. > 1. The mozilla compiled lightning uses a newer glibc than is available > in EL5 ... therefore it will not work with the EL5 Thunderbird. There > is a thunderbird-lightning package in EPEL testing for EL5 > (thunderbird-lightning-2.6.4-1.el5.x86_64.rpm) that should address this > issue. The upstream mozilla compiled plugin works for EL6. Here is the > EL5 x86_64 link to download: This is still broken for my use case (Lightning plus "Exchange 2007/2010 Calendar and Tasks Provider 3.1.3). Launching tb from a terminal, when you configure the calendar and either enter the settings manually, or select Exchange autodiscovery, then click on "Check server and mailbox" or "Perform autodiscovery", resp., the following errors are shown, resp.: 1st-setup: Error: Warning: Error during creation of erPrimarySMTPCheckRequest. Err=ReferenceError: erPrimarySMTPCheckRequest is not defined or 1st-setup: Error: Warning: Could not create erAutoDiscoverRequest. Err=ReferenceError: erAutoDiscoverRequest is not defined > 2. External http, https, and ftp Links may not work from thunderbird: [...] This works, although I didn't try if it works without.