The target server appears to be downgrading
the connection from TLS 1.2 to TLS 1.0:
[0958:0006-0C20:wrepl] 2016/03/28 13:06:12.79 SSLEncodeClientHello>
We offered SSL/TLS version TLS1.2
(0x0303)
...
[0958:0006-0C20:wrepl] 2016/03/28 13:06:13.34 SSLProcessServerHello>
Server chose SSL/TLS version TLS1.0
(0x0301)
but it is still claiming to support
the extended_master_secret (RFC 7627), which Domino offered over TLS 1.2:
[0958:0006-0C20:wrepl] 2016/03/28 13:06:13.34 SSLProcessServerHello>
Server chose SSL/TLS version TLS1.0
(0x0301)
[0958:0006-0C20:wrepl] 2016/03/28 13:06:13.34 SSLProcessServerHello>
Server chose cipher spec ECDHE_RSA_WITH_AES_256_CBC_SHA (0xC014)
[0958:0006-0C20:wrepl] 2016/03/28 13:06:13.34 SSLProcessServerHello>
Extensions found in this message
[0958:0006-0C20:wrepl] 2016/03/28 13:06:13.34 SSLProcessServerHello>
Received extended_master_secret
extension
I am shocked to hear about a server
that doesn't support TLS 1.2 (RFC 5246, from August 2008) but does support
RFC 7627 from last September! I'm not certain that combination is
even allowed by RFC 7627 - I'd have to check to be sure.
Setting SSL_DISABLE_EXTENDED_MASTER_SECRET=1
in your notes.ini will disable extended_master_secret support in Domino
which should fix your problem until you can get the remote server upgraded
to support TLS 1.2.