Re: Can we back up a bit and ask some basic questions? An alternate model

At 7:07 PM -0500 2/15/03, Martin Duerst wrote:
>At 10:31 03/02/15 -0800, Paul Hoffman / IMC wrote:
>
>>>(a) We define a new SMTP extension.  For purposes of discussion, 
>>>let's call it UTF8ADDRESSES.
>>
>>Therefore IMAA-UTF8 cannot achieve wide use until this extension is 
>>nearly universally adopted. When you get a business card from a 
>>colleague that has an internationalized email address, you can 
>>probably assume that their MTA supports UTF8ADDRESSES, but there is 
>>no way for you to know if your own MTA supports it, so you don't 
>>know if you can send him or her mail.
>
>Well, I think we can distinguish the following main situations here:
>(taking Japanese as an example)
>
>1) You don't know Japanese, so you won't even try.
>2) You have such an address yourself, and if your MTA supports it
>    on incoming mail, the chances are high it will work for outgoing mail.
>3) You have tried it for another, similar, address, and it failed,
>    so you won't try it again unless you have good reasons to assume
>    it might have improved.
>4) You'll give it a try, and see what happens. You might also
>    cc the mail to the older (ASCII-only) address to make sure.

Agree, almost. That last sentence makes an assumption that is not warranted.

>>With IMAA-UTF8, you always need to know that the originating MTA 
>>supports UTF8ADDRESSES. If you are a road warrior, you would need 
>>to know if your on-the-road ISP's MTAs support UTF8ADDRESSES before 
>>you could send mail to an IMAA-UTF8 address. Of course, you have no 
>>control over this.
>
>Well, I have my 'on-the-road MTA', but I don't use its MTA.
>SMTP after POP and now SSH tunneling work fine fine for me,
>and wouldn't be affected. Similar for VPNs that many companies
>use these days for security reasons. Of course, individual
>mileage may vary.

So IMAA-UTF8 is only for experts who know how to use tunneling. No, thank you.

>>With IMAA-UTF8, if a company has an MTA that supports 
>>UTF8ADDRESSES, and they want to add a firewall that has an SMTP 
>>proxy, that proxy must support UTF8ADDRESSES. Today, companies can 
>>safely add firewalls that have SMTP proxies that have fewer ESMTP 
>>services than the MTA for which they front.
>
>Your last sentence can be interpreted in two ways. In the trivial way,
>such SMTP firewalls are always possible if the ESMPT service is not
>needed. That wouldn't be different for IMAA-UTF8.

Yes, it would be quite different. Most ESMTP extensions are 
non-critical; the message can still be delivered if the extension is 
not available. IMAA-UTF8 would be critical: if any MTA in the path 
didn't support it, that MTA would have to make out-of-band guesses 
about how to deliver the message or would have to send back a 
"message is undeliverable" response. Both are pretty bad, and I'm not 
sure which is worse.

>The other interpretation would raise some questions: Do you want to say
>that all functionality offered by current ESMTP options can be tunnelled
>over MTAs that don't offer these options?

No, of course not.

--Paul Hoffman, Director
--Internet Mail Consortium