When replying to a message or creating a new message, the "From:" address is
not properly quoted when required.

For example, the "From:" address is shown as:

  From: LeJacq, Jean Pierre <jeanpierre.lejacq@quoininc.com>

It should be:

  From: "LeJacq, Jean Pierre" <jeanpierre.lejacq@quoininc.com>

A reliable workaround is to select the identity from the drop down list and
then the quotes are added.

This seems to be a regression of the following bug but is extended to new
messages, not only when replying. It was fixed as some point but seems to have
been reintroduced.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=730048