Re: [Extra] Is this a plausible IMAP extension ?

Arnt Gulbrandsen <> Wed, 27 February 2019 06:32 UTC

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From: Arnt Gulbrandsen <>
To: "John R. Levine" <>
Date: Wed, 27 Feb 2019 07:32:24 +0100
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Subject: Re: [Extra] Is this a plausible IMAP extension ?
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On Wednesday 27 February 2019 04:06:36 CET, John R. Levine wrote:
> There is this thing called BIMI that is being debated elsewhere 
> in the IETF.  Leaving aside for the moment the issue of whether 
> it's a good idea in the first place, it invents an IMAP feature 
> that seems dodgy to me.
> When an MTA that supports BIMI delivers a message into the 
> mailstore, it adds a header that tells MUAs where to find a logo 
> to show next to the message.  (Think of it as x-face for 
> corporations.)  Since bad people could phish victims with their 
> own header with a misleading image, BIMI invents a new IMAP flag 
> that only the delivery MTA can set on messages where it has 
> added a virtuous header.  An MUA can test it to decide whether 
> to show the logo.  Other IMAP or POP clients can't set the flag, 
> but it presumably stays with the message if it's moved from one 
> folder to another.

There is a sort of expectation with IMAP that you can copy messages. That 
you can copy your entire mail archive from fastmail to gmail and the result 
will work as before. There are programs to do this, imapsync for example, 
and doesn't one of the big MUAs have this builtin, too?

BIMI wouldn't. With BIMI, the copy would be degraded, not complete.