^--- Okay. But I don't follow how that's different?

If you're manually grooming the length of an email, it's not "natural".

When a friend emails you (okay, okay... I know... who the hell actually EMAILS friends these days)... but when an out of touch relative who still doesn't SMS or Facebook yet, when THEY email you... it's full width.

And we read it just fine.

As soon as you get into artificially grooming an email, I think you're back to square one of "is it coming across genuine"?

In the IM space, it's not as relevant.

We ALL know you pressed Send in Aweber.

Full width or not... we all know you've got us in one of the mainstream mailing list services.

But when selling to a non-savvy market, ESPECIALLY if you're already attempting to appear "genuine" with customization fields, then why chop the lines?

55 chars or 700 pixels (which is what?? About 75 chars I think?)... it's irrelevant in my opinion. You're still grooming the look and feel of it, making it unauthentic to the reader.