Pros and cons of PGP/MIME for outgoing e-mail?

Bjarni Runar Einarsson bre at
Mon Nov 24 21:48:39 CET 2014

Hi Simon, thanks for the comments.

Simon Ward <simon at> wrote:
> I currently use Thunderbird and Mutt, both of which can open "emails
> within emails" as MIME parts, but I'm fairly certain Outlook from Office
> 2002 coped with them too. Granted, it's still an extra step with those
> MUAs, but all they need to do is handle MIME, which is a container just
> as much as Zip is. Why introduce Zip as yet another container, and yet
> another thing for diverse MUAs to handle instead of using one that many
> MTAs already support?

The reasons I don't want to put the text part in a container at all, but
am willing to consider doing so for attachments are as follows:

1. Mail clients have user interfaces that are at least somewhat
optimized for conversations, like the one we are having now. Moving the
text part into a container (rfc2822 or otherwise) breaks that flow for

2. For attachments, that flow is less entrenched. Granted, many MUAs
will open an application when you click on an attachment, but others
will save to disk, still others will offer a choice. Adding an extra
step here (interacting with the container) is off the critical path of
how the mail client is most often used. It is still an extra step
though, and extra code to write in the MUA, which is one of the reasons
I not sure about the merits of using a container at all.

Note that if the container is a ZIP file, that will work without extra
tools on all modern OSes (if I recall, I need to double-check a fresh
Windows install), but that is certainly not true for RFC2822 or tar
(which was suggested on the Hacker News thread about my blog post). Using RFC2822 will work if you have a nice desktop mail client, but if you do, then you also have (the option of) PGP/MIME support and are not the user I am trying to help with this proposal.

As stated in my post - my proposal makes life marginally worse for
people with PGP/MIME compliant MUAs (working with attachments becomes
less fun), but better for everyone else. I haven't come up with a way
around that yet, short of shipping 2 of everything in each message. :-)

 - Bjarni

I make stuff:,
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