SMTP no-such-user issues

Frank Bulk - iNAME frnkblk at
Tue Jun 17 12:45:55 UTC 2008

Once you've performed a full capture on port 25, Wireshark does a nice job
of providing an option to extract the relevant conversation by
right-clicking on just one packet in that conversation and choosing
something called "Follow the TCP stream", I believe. 


-----Original Message-----
From: Steve Bertrand [mailto:steve at] 
Sent: Tuesday, June 17, 2008 7:44 AM
To: frnkblk at
Cc: nanog at
Subject: Re: SMTP no-such-user issues

Frank Bulk - iNAME wrote:
> Please share a packet capture of a working and not working SMTP exchange.

In order to provide the highest amount of clarity, could you recommend a
specific set of tcpdump command line args that I should use?


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