[sajagi]

Even if the IP address was guaranteed static then I wouldn't dare recommending admins to add an exception to firewall. That would certainly be a very bad practice. There are tools available (mentioned in the comments around) that do the same job and can be run in the DMZ (the question is, would anyone go through the source code and verify the tool does not contain any malicious code?).

[jacquesm]

Excellent, so how about the opposite: tell people on the website not to make an exception for your service.

[sajagi]

I am tempted to not interfere with the darwinian process ;) But seriously, we'll probably add some note like that.