Whoever told you that the Eris was bad for e-mail was just projecting a personal bias. Probably because it lacks a hardware keyboard. More on that in a second.
As far as e-mail client support, last I checked all of the Verizon Android offerings have Exchange support, though I may be corrected. I don't personally use Exchange, but a lot of businesses do. If Gmail support is desired, any phone will do just fine.
If your husband enjoys having a real hardware keyboard (very common on Blackberries outside of the Storm line), then the Motorola Droid is probably your best bet. I found the hardware keys flat and hard to hit accurately without staring at it. The Eris and Incredible only have on-screen "software" keyboards. I personally find these easier to use, but most users find them more difficult.
Just a note: The Droid Eris is discontinued now, hence why they're so cheap. I have one and use it for work/play and have no issues. The Droid is getting replaced by the Droid 2 here in the next few months, so the prices should be coming down on those too. If your husband wants to have a top-end device the Incredible, Droid X, or Droid 2 will probably be the best bets. Just note that none of them are readily available as of this writing. The Incredible is on backorder until late July, the Droid X comes out on July 15th, and the rumors are that the Droid 2 will be out in August.