Hi,

Dovecot allows practically everything even if you don’t enable UTF8=ACCEPT. From memory there are only two differences:

Dovecot won’t allow a well-behaved MTA such as Exim or Postfix to deliver mail with SMTPUTF8. Postfix has an option to override that, I’m sure there are other ways as well. I doubt that many people enable this option, or one of the other ways.
If a message arrives From: blå@xn--gr-zia.org, such as you might see if the message is from Exchange, then you may see xn- -gr-zia in the user interface of a mail reader, and a search for grå may or may not find the message. If UTF8=ACCEPT is enabled you should only ever see grå and searching should work reliably.

Dovecot’s handling of unexpected Unicode is so liberal that some clients protest 😉

Arnt

From: "John R. Levine" <johnl@iecc.com>
Date: Monday, 27 January 2025 at 18:18
To: Arnt Gulbrandsen <arnt.gulbrandsen@icann.org>, Dr Ajay Data <ajay@data.in>, "ua-eai@icann.org" <ua-eai@icann.org>
Subject: Re: [UA-EAI] Re: [Ext] Re: Dovecot 2.4 released today

On Mon, 27 Jan 2025, Arnt Gulbrandsen wrote:

Sorry, I assumed that John’s question was about IMAP clients. I agree that there are more UA-ready mail clients in general, even if I’m a little surprised by that list. Last time I tested the ios app (Apple’s, I assume) it was unable to reply correctly, and since I’m typing this into Outlook, let’s test… nope, can’t add a Unicode address to this message, see screenshot. The previous version could do it, and OWA can too.

When I was testing EAI software a while ago, I found almost no IMAP

clients or servers that had the EAI extensions, but it hardly mattered

since they handled EAI messages and UTF-8 folder names using the regular

non-EAI methods. Dovecot, at least up to 2.3, only allows ASCII user

names and passwords (I looked at the code.) In 2.4 it should allow them

if your client turns on the extension. Any idea if it does even if you

don't?

Regards,

John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",

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