how to allow mobile user to send email with getting blocked

[Harondel J. Sibble]

Just wondering what you all suggest is the best way to deal with the 
following.

Mailscanner machine at the enge of the network, internal imap mailserver, 
users with mobile phones connected via imaps to the internal server with 
various mail clients.

SMTP Auth is in place for all users to send email.

Approx 50% percent of the time, the users on one cell provider (Mobilicity) 
have their mail marked as spam and quarantined, generally users on Rogers, 
Fido, or Telus don't have the same problem or not to same extent, eg

SpamAssassin Score:	4.42
Spam Report:	
	Score	Matching Rule	Descriptioncached	not	 
	score=4.423	 
4	required	 
-2.60	BAYES_00	Bayesian spam probability is 0 to 1%
-3.30	KHOP_DNSBL_ADJ	 
-1.50	KHOP_THREADED	 
1.96	RCVD_IN_BL_SPAMCOP_NET	Received via a relay in bl.spamcop.net
1.70	RCVD_IN_HOSTKARMA_BL	 
2.00	RCVD_IN_MSPIKE_BL	 
0.01	RCVD_IN_MSPIKE_L3	 
2.40	RCVD_IN_PSBL	 
0.62	RCVD_IN_SORBS_WEB	SORBS: sender is a abuseable web server
3.03	RCVD_IN_XBL	Received via a relay in Spamhaus XBL
0.10	RDNS_NONE	Delivered to trusted network by a host with no rDNS

I've considered client ssl certs but not all the devices/mail client apps 
support this so not really a solution?

What would you suggest is the best way to keep their legitimate emails from 
being blocked by the mailscanner machine.


-- 
Harondel J. Sibble 
Sibble Computer Consulting
Creating Solutions for the small and medium business computer user.
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