Re: Can't send e-mail via `smtpmail'

[Alexander Shukaev <haroogan@gmail.com>]

>> Date: Mon, 13 Jul 2015 19:09:01 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>>
>> > Date: Mon, 13 Jul 2015 15:29:17 +0200
>> > From: Alexander Shukaev <haroogan@gmail.com>
>> > Cc: help-gnu-emacs <help-gnu-emacs@gnu.org>
>> >
>> > Tried with the 'gnutls-cli':
>> >
>> > $ gnutls-cli --verbose --starttls --tofu -p 587 mail.gandi.net
>> > Processed 161 CA certificate(s).
>> > Resolving 'mail.gandi.net'...
>> > Connecting to '217.70.184.11:587'...
>> > Connecting to '2001:4b98:c:521::11:587'...
>> > Could not connect to 2001:4b98:c:521::11:587: Connection refused
>                          ^^^^^^^^^^^^^^^^^^^
> Btw, the above is an IPv6 address, whereas my port of GnuTLS only
> supports IPv4.  Maybe that's the problem here.  (I know nothing about
> these issues.)
>
It's amazing...  Today I'm in another city.  I didn't change anything
in my configuration, only the internet end-point from where I send
e-mails, and now it works:

$ gnutls-cli --verbose --starttls --tofu -p 587 mail.gandi.net
Processed 161 CA certificate(s).
Resolving 'mail.gandi.net'...
Connecting to '217.70.184.11:587'...

- Simple Client Mode:

- Received[40]: 220 relay.mail.gandi.net ESMTP Postfix
EHLO
- Sent: 5 bytes
- Received[27]: 501 Syntax: EHLO hostname
QUIT
- Sent: 5 bytes
- Received[15]: 221 2.0.0 Bye
- Peer has closed the GnuTLS connection

Similarly, sending with `smtpmail' works as well.  Kek, how come?
Something wrong with DNS at the previous place?