Mails getting rejected as spam

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The review of this web host was started by squelch666 on 2009-12-17 05:49:48:

I have a client whose emails are getting rejected as spam. The source code on the client side has this analysis:

Content analysis details: (10.3 points, 5.0 required)
pts rule name description
—- ———————- ————————————————–
1.0 EXTRA_MPART_TYPE Header has extraneous Content-type:…type= entry
0.5 FH_HELO_EQ_D_D_D_D Helo is d-d-d-d
2.9 HELO_DYNAMIC_IPADDR Relay HELO’d using suspicious hostname (IP addr
1)
1.6 MISSING_HEADERS Missing To: header
0.0 HTML_MESSAGE BODY: HTML included in message
0.1 RDNS_DYNAMIC Delivered to trusted network by host with
dynamic-looking rDNS
0.0 DYN_RDNS_AND_INLINE_IMAGE Contains image, and was sent by dynamic
rDNS
4.2 FORGED_MUA_OUTLOOK Forged mail pretending to be from MS Outlook

The server is an ubuntu VPS but the emails are currently being sent from outlook express. I assume that it is essentially a sendmail issue, but I have to admit I am largely ignorant about sendmail. What should I do?

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