FWIW:
On Mon, 11 May 2020, at 21:17, Alexander Vasarab wrote:
When I send mail, it fails the first time, and then as long as I
immediately resend, it succeeds (over TLS, thankfully).
I have recently come along this very same pattern when using command
line tools like curl or lynx to access https. The observed pattern
includes the ~10s you mentioned earlier and the fact that it's not
related to versions of TLS or SSL libraries like OpenSSL.
On Tue, 12 May 2020, at 05:40, Viktor Dukhovni wrote:
Indeed the server slams the TCP socket closed after receiving the
client's RCPT command. Unclear why.
This is also what I observed. For the record a typical curl error
message
curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to server:443
Unfortunately, I haven't yet come along a server where I felt
comfortable testing the heck of this out of it. Plus, the servers
where I have observed it did not show the same behavior over the
course of my attempts at debugging it (several hours). So, yes, very
unclear what and why.
One admin I contacted suspected that their provider was trying to
mitigate DOS attacks. But that's too vague an explanation for my
taste.
--
-- Andreas
:-)
