Re: [exim] TLS on connect and Microsoft MUA confusion.

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Author: Phil Pennock
Date:  
To: Chris Kruger
CC: exim-users
Subject: Re: [exim] TLS on connect and Microsoft MUA confusion.
On 2012-06-26 at 10:11 +0800, Chris Kruger wrote:
> "SMTP protocol synchronization error (input sent without waiting for
> greeting):"
>
> If understand correctly this is characteristic of tls on connect problems ?


Nope; that's a protocol lockstep issue. In SMTP, the server speaks
first, but the client isn't waiting for the banner. This behaviour is
common for pump&dump spammers, so seeing in on port 25 is bad.

You can turn this off globally, for all ports, using the
"smtp_enforce_sync" option -- set it false.

You probably instead want to define a acl_smtp_connect ACL, which sets
"control = no_enforce_sync" if the port is 465.

----------------------------8< cut here >8------------------------------
# main section

acl_smtp_connect = acl_connect

begin acl

acl_connect:
  warn   condition = ${if =={$received_port}{465}}
         control = no_enforce_sync


accept
----------------------------8< cut here >8------------------------------

-Phil