It seems my server is having X.509 certificate problems, so the problem isn't at the client-software end.
From: Kasper Føns [mailto:kfoens@...]
Sent: Thursday 10 May 2012 07:11
Subject: Re: [Hpop-users] Exchange 2010 POP3 Server and TLS
As you explain in the Exchange forum, you are using implicit TLS which runs on port 995.
It should be correct to connect to it on port 995 and supply true for the useSsl parameter. As seen in your second link, Exchange requires implicit TLS - which means that when connected, the client should negotiate TLS connection without sending the "STARTTLS" command (STARTTLS is unsupported in POP3). OpenPop just does that when useSsl is set to true.
I can see that you tried using Outlook Exchange as well - failing as well. To me it seems like the server is set up wrong then?
Have you restarted the server once you changed the configuration?
So I am inclined to say that OpenPop works, and that the server is set up wrong somehow.
However, looking at your settings in your Exchange post, everything seems fine (without knowing much about Exchange server)...
Ohnay - this wasn't very helpful :(
On 10-05-2012 03:15, David Rees wrote:
> (I'm using a build of OpenPOP taken from a snapshot of the source on
> I recently upgraded my POP3 server to Exchange 2010 (with SP2) and it fails whenever I try to connect using SSL/TLS with this exception:
> IOException: The handshake failed due to an unexpected packet format.
> at System.Net.Security.SslState.StartReadFrame(Byte buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
> at System.Net.Security.SslState.StartReceiveBlob(Byte buffer, AsyncProtocolRequest asyncRequest)
> at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte buffer, AsyncProtocolRequest asyncRequest)
> at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
> at System.Net.Security.SslStream.AuthenticateAsClient(String targetHost)
> at OpenPop.Pop3.Pop3Client.Connect(String hostname, Int32 port,
> Boolean useSsl, Int32 receiveTimeout, Int32 sendTimeout,
> RemoteCertificateValidationCallback certificateValidator)
> This exception happens regardless of whether I connect on port 110 or
> port 995. I've crossposted this issue to Exchange's own forum:
> I did some reading and I think that the problem (on port 110, at
> least) is because Exchange expects explicit TLS which is documented
> I can provide details for my Exchange server if anyone feels like testing it.
> If this is the case, how long would it take to implement a solution?
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