Re: SMTPUTF8 in MAIL FROM command

On 30 Aug 2016, at 12:34, Jeff Wark wrote:

> I have one customer that is attempting to send email using Outlook 
> 2016 (I think).  Their MAIL FROM command looks like this:
>
> 10:09:47.618 4 SMTPI-548278([1.2.3.4]) cmd: MAIL FROM: 
> <[email protected]> SMTPUTF8
> 10:09:49.621 4 SMTPI-548278([1.2.3.4]) rsp: 555 syntax error in MAIL 
> FROM parameters
> 10:09:52.136 4 SMTPI-548278([1.2.3.4]) cmd: QUIT
>
> Is that some standard that we (CommuniGate server users) should be 
> accepting at this point (the SMTPUTF8 string at the end of the 
> command)?

No. No version of CGP supports SMTPUTF8. SMTPUTF8 is not indispensable 
for anything, or it would have happened a decade faster. No mail server 
that does not support SMTPUTF8 should accept it as an extra argument to 
MAIL. This is true of all SMTP extensions that use MAIL arguments: it 
would cause worse issues further along if receivers just accepted 
extensions they don't really do.

> I am using CommuniGate 6.0.11 right now, but I can see no mention of 
> the string SMTPUTF8 in the history for versions 6.0 or 6.1.
>
> According to https://en.wikipedia.org/wiki/Extended_SMTP#SMTPUTF8, one 
> feature of this extension is that email addresses containing non-ascii 
> characters can be used.  However, not many mail servers seem to 
> support it.

Yes. There is also a clear simple mechanism by which clients can tell 
whether SMTPUTF8 is supported before just trying it, which is the same 
mechanism ALL SMTP extensions use. It would take a totally incompetent 
MUA developer to send SMTPUTF8 in MAIL after not seeing it in the EHLO 
reply.

So, yeah: Only Microsoft. No surprise there.

> Again, looking in my logs, I can see only one customer attempting to 
> use it at this point.
>
> Anyone else have experience with this?

Not with CGP, but I run Postfix instances that have it enabled. It is 
pretty rarely used. I don't believe I've ever accepted a message using 
it, but those are high-spam low-total volume systems.


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