> From Ron Gorodetzky Wednesday, July 04, 2007 8:27 PM
>
> I've never really had the need to tweak default settings too 
> much though after investigating a bit more, I'm not sure why 
> not.  I'm going to have to reevaluate my other setups.
> 
> These are the settings I've chosen for timeouts.  Are they 
> too ambitious?  
>   command_timeout = 20s
>   connect_timeout = 20s
>   data_timeout = 30s
>   final_timeout = 1m

Yes, too ambitious in my opinion. You will probably quite a few hosts that you 
connect to that cannot keep up with this. Systems doing callouts may not be 
able to reply to a RCPT TO or MAIL FROM command in 20 seconds, systems going 
SMTP-time virus and spam scanning may have delays during the data and final 
phases. You can't assume that other systems are doing nothing but simply 
spooling mail to disk.


> I found that at least one of the misbehaving messages was 
> hanging on the
> following:
> 
> initializing GnuTLS as a client
> generating 512 bit RSA key...
> selecting on subprocess pipes
> selecting on subprocess pipes
> ...
> 
> After searching a bit online, some said to make sure (on 
> debian) gnutls was installed, or to make sure you don't have 
> entropy starvation, pregenerating exim.key and exim.crt 
> files, etc.  Nothing seemed to make any difference.  So I 
> decided to just turn off tls for remote_smtp. Like
> so:
> 
>   hosts_avoid_tls = *
> 
> That seemed to do the trick.  I'm not entirely sure why the 
> other supposed fixes didn't work.  I certainly support the 
> use of tls (I use it for smtp between client apps when I 
> setup a mail server with
> authentication) so it feels odd turning it off.  Is it common 
> practice to leave it on for server to server mail exchange?  
> Should I expect a lot of rejected mail using this setting?

I doubt you will see any rejected mail. Most public mail hosts use TLS on a 
"best effort" basis and fall back to unencrypted if it is not supported.

You may well have an entropy issue. I don't know the specifics of what to do 
about it on Debian.

David


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