Opera

To call thunderbird on mailto: Links, I set the the email program setting to "Use specific e-mail client" which is set to /home/cweiske/scripts/tb-compose

Example 2.5. /home/cweiske/scripts/tb-compose

#!/bin/sh
# dont' rename it to "thunderbird-compose" or so
# cause the thunderbird will be found in the process list

if pgrep -u `whoami` thunderbird
then
        /opt/MozillaThunderbird/thunderbird -remote "mailto($1)"
else
        /opt/MozillaThunderbird/thunderbird -compose mailto:$1
fi

Here is the predefined subject and text missing, but that's got to be made another time...