Incoming mail question, what's happening?

[Feek]

Every 15 minutes, 24/7 I get the following connection to my mail router.

Mon 2007-05-07 12:59:59: Session 1057; child 1; thread 3324
Mon 2007-05-07 12:59:48: Accepting SMTP connection from [195.157.130.161 : 41779]
Mon 2007-05-07 12:59:48: Performing PTR lookup (161.130.157.195.IN-ADDR.ARPA)
Mon 2007-05-07 12:59:48: * Error: Name server reports domain name unknown
Mon 2007-05-07 12:59:48: * No PTR records found
Mon 2007-05-07 12:59:48: ---- End PTR results
Mon 2007-05-07 12:59:48: --> 220 all-one-word.com ESMTP MDaemon 9.5.2; Mon, 07 May 2007 12:59:48 +0100
Mon 2007-05-07 12:59:49: <-- EHLO titian.gsb.co.uk
Mon 2007-05-07 12:59:49: Performing IP lookup (titian.gsb.co.uk)
Mon 2007-05-07 12:59:49: * Error: Name server reports domain name unknown
Mon 2007-05-07 12:59:49: ---- End IP lookup results
Mon 2007-05-07 12:59:49: EHLO/HELO response delayed 10 seconds
Mon 2007-05-07 12:59:59: --> 250-all-one-word.com Hello titian.gsb.co.uk, pleased to meet you
Mon 2007-05-07 12:59:59: --> 250-ETRN
Mon 2007-05-07 12:59:59: --> 250-AUTH=LOGIN
Mon 2007-05-07 12:59:59: --> 250-AUTH LOGIN CRAM-MD5
Mon 2007-05-07 12:59:59: --> 250-8BITMIME
Mon 2007-05-07 12:59:59: --> 250 SIZE 0
Mon 2007-05-07 12:59:59: Connection closed
Mon 2007-05-07 12:59:59: SMTP session terminated (Bytes in/out: 23/218)

That IP relates to Granada Sky Broadcasting Ltd. Not sure if this is Sky itself. I don't have any internet stuff with them and I don't recall ever giving them an email address. There are never any attempts to send anything, it's always just the same as above.

The 161 IP is the University of Missouri-Columbia? wtf?

Any idea what's happening there?