Do "ls -a" to see the hidden directories. Since Seamonkey is related to Mozilla/Thunderbird, I'd expect to find one of the following:
In one of these, you'll find a profile name that looks something like this: "xuxkj8y5.default". Open this directory and you'll find your mail folder.
You will not find the format particularly friendly, but it's easy enough to write a script to extract things. (Even easier to just read it with the mail client.....