K9 won't connect to server

[CMeys]

I've just installed K9 on my Evo 3D running ICS.

I've tried to setup POP email accounts on both comcast.net and gmail.com (my gmail account is set to POP3). No matter what account I try, I receive this error message. It happens both if I let K9 automatically configure the account or if I do it manually (and I've triple checked that my settings are correct). Phone has both wifi and mobile network running. Default email app has no problems.

How do I fix this?