[stunnel-users] Stunnel for secure email connections

Lee uklee at ukonline.co.uk
Sun May 24 16:38:37 CEST 2009

Hello Guy and thanks for your reply.

Guy wrote:
> So you have...
> Client (MUA) <=> Avast and/or Popfile <=> Stunnel <=> Server (MTA)
Yes, that's right.

I've looked at the mail headers more, and tried some of the packet 
sniffing/log methods, but I'm not really having any more success in 
understanding / pinpointing a secure connection.

I think I'm not going to be able to grasp the issues here, so maybe it 
is simpler if I could simply state what I have done, to check that it 
should be correct;

I installed both OpenSLL and Stunnel. I haven't changed anything from 
the OpenSLL install.
In stunnel.conf, I currently have the file shown at the bottom of this 
I have changed settings in Thunderbird's mail accounts (hosts and ports) 
and in Avast Anti-Virus email scanner. (its redirected ports settings)
Adding Popfile (a local mail 'tagging' proxy) back into the equation has 
required some further tweaks to Thunderbird's ports and server usernames 

As I said earlier, all seems to be working, in that my 'chain' appears 
to be having an effect.
However should I be considering anything else to make this process 
meaningful, such as certificates or security issues?
My only motive for using Stunnel and OpenSSL is to allow Avast email 
scanner to scan _all_ emails, including those it normally cannot scan 
due to their servers requiring me to use a secure connection. So, if I 
am doing this 'new' process wrongly or opening up security issues due to 
not understanding it, I would be better off reverting to how it was 
previously, seeing as the mail servers I use state they do virus 
scanning anyway.

Thanks again,

my current stunnel.conf  :-


accept =
connect = pop.mail.yahoo.co.uk:995

accept =
connect = pop.tools.sky.com:995

accept   =
connect  = pop.tools.sky.com:995

accept  =
connect = pop.mail.yahoo.co.uk:995





avast! Antivirus: Outbound message clean.
Virus Database (VPS): 090524-0, 24/05/2009
Tested on: 5/24/2009 15:38:38
avast! - copyright (c) 1988-2009 ALWIL Software.

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