Is there any way to make Thunderbird only prompt you for a password once a session?

[sjak]

Hey,
I have been doing computer work for people lately and I have always been recommending Thunderbird to my clients. I now have one client who demands that I only have Thunderbird prompt for a password once a session. For the life of me, I cannot find any way to do this, and Thunderbird's support website has been no help. =/