Thunderbird is a cross platform email client, Lightning is a calendering add-on. Lightning will be integrated into Thunderbird 3. Thunderbird installation is straightforward, Lightning is installed from Thunderbird’s ‘Tools/Add-ons’ menu.
DavMail is an Exchange gateway that wraps standard protocols like IMAP around the proprietary interfaces to Exchange. DavMail setup is straightforward, following the instructions on it’s website, all I had to provide was the OWA URL.
To configure IMAP in Thunderbird all I had to do was specify a server name of localhost and port of 1143, not 143. To configure CalDAV I specified a CalDAV location of http://localhost:1080/users/me@mydomain.com/calendar To configure SMTP for outgoing mail I specified localhost port 1025, not 25.
I couldn’t figure out how to use DavMail LDAP, the documentation is too cryptic. Instead I configured a Thunderbird address book to directly access Active Directory, which works only locally on the LAN. With the address book available autocompletion works also.
Trying to replicate the directory for offline access did not work for me, however. This is supposed to be fixed in a later release. To work around not having the Exchange address book offline I installed Email Address Crawler which instantly scooped every to or from address from my existing mails into an address book. I took this home and it worked as expected: I could send and receive mails and had a limited address book.
Having proven this configuration under Windows I installed Ubuntu in a VM and used Synaptic to install Thunderbird. Lightning and DavMail are downloaded and installed the same way as on Windows. I did, however, run into a defect and workaround installing Lightning.
This solution seems to work OK, but I noticed some issues with the HTML email editor. This is improved in Thunderbird 3, which went into its fourth beta release a few days ago.