[Slackbuilds-users] Email rejected during submission

Franzen slackbuilds at schoepfer.info
Tue Nov 7 13:27:13 UTC 2017

On 05.11.2017 00:18, Erik Hanson wrote:
> On 11/04/2017 04:52 PM, johannes at schoepfer.info wrote:
>>> The address verification probes are done on the SBo web server, not
>>> on the mail server.
>> Ok, then the web server does something with hotmail's mx servers, are
>> there logs?
> No, it's not an MTA. It does this:
> lookup MX and connect, wait for 220
> send HELO slackbuilds.org
> wait for response
> send MAIL FROM: <slackbuilds-users at slackbuilds.org>
> wait for 250
> send RCPT TO: <$Email>
> wait for 250
> send QUIT
> If either response is not 250 then it's considered rejected. It's very
> simple, follows the RFC, and works 99.99% of the time. I'm not
> personally interested in any suggestions for making it more robust, as
> I'm confident that would only raise the failure rate until we've either
> written an entire MTA or unnecessarily swapped it out for a proper one.

No suggestion for anything, just fyi, it seems hotmail enforces 
starttls, the smtp dialog works e.g. when openssl is used for the 
connection. It doesn't work if "rcpt to" is written in caps in 
conjunction with openssl:

openssl s_client -starttls smtp -crlf -connect 
helo mail2.0ur.de
250 SN1NAM04FT013.mail.protection.outlook.com Hello []
mail from: <slackbuilds at schoepfer.info>
250 2.1.0 Sender OK
rcpt to: <jorge.giner at hotmail.com>
250 2.1.5 Recipient OK
221 2.0.0 Service closing transmission channel

Enforced starttls may occour more often in the future.


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