I downloaded the file for Rat Infested Mailbox after donating to the font submitter. I've taken the file to six sign shops to have my sign made and none of them can use the file. I contacted the font submitter and he cannot help me. Can anyone?

What platform do you use?
What is the format of the font?

It seems ludicrous that they can't use the fonts. . .
almost seem like a won't scenario to me.

What seems to be the problem? Why can't they use Rat Infested Mailbox? Why can't David help you?

The embedding setting for the font are "Only printing or previewing of the font is allowed (read only)". These settings can be changed by the font designer, or by someone who has a font editor. In either case, a new version of the font would have to be generated to use it for other purposes.