That sounds promising. Is this a feature that wasn't implemented? I tried just adding ":format-flowed: true" to config.yaml, with no apparent effect. 

On Sunday, July 19, 2015 at 3:50:21 AM UTC-4, Gaute Hope wrote:

Dave Unger writes on July 19, 2015 0:07:
> I've noticed that the line breaks in emails that I send from Sup look bad
> on mobile devices (or at least they look terrible on the gmail android
> app). The problem seems to come from a collision between the hard
> line-wraps that Vim inserts and the wrapping that the android client uses
> to display the message (basically the default gmail client doesn't reflow
> the paragraphs).
>
> Is there something I can do on my end to send emails that other readers
> (especially those more geared toward html messages) will have an easier
> time displaying? I was playing around with just setting up vim for soft
> wrapping, but I don't love that solution (for vim-based reasons).
>
> Thanks,
> Dave
>

This could be related to format-flowed, which is not set to true in sup.
Check out this old PR: https://github.com/sup-heliotrope/sup/pull/228

-gaute