I guess in the real world, the conversation would have gone something like this :
Me: You might not want to have a free email account listed on your sign.
Tech: Why's that?
Me: Well, I went to a local government event, where they taught people how to do business with the local government and in their presentation, they specifically said they did not respond or read emails from free email accounts. They didn't say why, they just stated it in the meeting. I didn't think much of it, as we didn't use one, but not too long after that, I went to a pre-bid meeting for a hospital, and in that meeting they said the same thing.
Tech: Humm, that's interesting, I'd not heard of anything like that before.
Me: Me either. Want to go grab a beer?
Tech: Sounds good to me.