STARTTLS over port 25 failes with error:1408F10B:SSL

[rabin-io]

Trying to send the mail via mail relay which only support 1.1 & 1.2 TLS fails with this message,

SSL/TLS: SSL connect attempt failed error:1408F10B:SSL routines:ssl3_get_record:wrong version number

running this command:

smtp-cli --server=mx3 --ipv4 --verbose \
             --from=XXX \
             --to=YYYY \
             --subject="TEST" \
             --body-plain=/etc/os-release \
             --ssl

Connection from 4.3.2.1:57890 to 1.2.3.4:25
Starting SMTP/SSL...
687 SSL/TLS: SSL connect attempt failed error:1408F10B:SSL routines:ssl3_get_record:wrong version number

[mludvig]

I suspect your openssl library or perl ssl modules don’t support TLS 1.1/1.2. Does this work?

openssl s_client -connect 1.2.3.4:25

What are your versions of openssl and of IO::Socket::SSL and Net::SSLeay perl modules?

Any chance I can test against your 1.2.3.4:25?

[rabin-io]

The above command fails as port 25 is just a clear text, but running this commad works

openssl s_client -connect testmx.rabin.io:25 -starttls smtp

you can test it your self.

[mludvig]

I see. Don't use --ssl with smtp-cli then, let it do STARTTLS (which is a default) and you'll be set:

~ $ smtp-cli --server testmx.rabin.io --verbose
Connection from 172.31.174.91:52090 to 192.115.4.132:25
[220] 'mx.isoc.org.il Microsoft ESMTP MAIL Service ready'
> EHLO localhost
[250] 'mx.isoc.org.il'
[250] 'PIPELINING'
[250] 'SIZE 204800000'
[250] 'ETRN'
[250] 'STARTTLS'
[250] 'ENHANCEDSTATUSCODES'
[250] '8BITMIME'
[250] 'DSN'
Starting TLS...
> STARTTLS     <=== here it automatically starts TLS and connection gets encrypted
[220] '2.0.0 Ready to start TLS'
Using cipher: ECDHE-RSA-AES128-SHA256      <=== see, it's using encryption
Subject Name: /CN=mx3.isoc.org.il
Issuer  Name: /C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
> EHLO localhost
[250] 'mx.isoc.org.il'
[250] 'PIPELINING'
[250] 'SIZE 204800000'
[250] 'ETRN'
[250] 'AUTH PLAIN LOGIN'
[250] 'AUTH=PLAIN LOGIN'
[250] 'ENHANCEDSTATUSCODES'
[250] '8BITMIME'
[250] 'DSN'
> QUIT
[221] '2.0.0 Bye'

Hope that helps.

[rabin-io]

Thanks for the clarification.