>>>>> "SJ" == Simon Josefsson writes:

 SJ> I could not find a more canonical specification of it.

Me too. Otherwise, I, probably, wouldn't want to change it.

 SJ> If it is added, IMHO it should not be advertised much or include a
 SJ> prominent warning in the docstring that changing it from the default
 SJ> can cause irritation.  Compare the bad behaviour caused by some MUAs
 SJ> that translate Re: etc.

Agreed.

---Vas