Rated 4 out of 5 stars

To get AutoCopy 1.0.1 to work with Thunderbird 3.0.3 I had to modify the install.rdf file (I opened up the downloaded .xpi with 7-zip then edited install.rdf)
Change to install.rdf:
Under the Thunderbird section, change the maxVersion to 3.0.3
3.0.3
Then save (also updates the archive) and install as normal.

This review is for a previous version of the add-on (1.0.1.1-signed.1-signed).