Re: quick & dirty alternate addresses

> That's interesting.  My MUA (Mutt) has no such trouble.  I've created
> another display-name test in the To: field of this message.  I wonder:
>
>  * Is the To: field of this message valid?

yes.

>  * If so, should MUAs be able to compose a reply to it?

yes, but given that many MUAs implemented RFC 2047 not by changing how 
header fields were displayed but by converting header fields containing 
encoded-words on the fly, and then using the converted form to compose 
replies,
it's unsurprising if MUAs don't do the right thing with it.

>  * If MUAs should be able to compose a reply to it, what is the proper
>    procedure

the proper procedure is to use the original message (not the form 
converted for display) to compose the reply.