Redmine

Hi everyone... Need a little help with this one please:

My Redmine installation is authenticating users off LDAP and I'm accepting e-mail Issue submission. Here is the alias I've created on my mailhost:

<user>: "|/root/scripts/rdm-mailhandler.rb --url=http://<FQDN> --key=<key> --project=<PROJECT> --tracker=Support --allow-override=tracker --unknown-user=accept"

This works for every user (thus far) except one in particular, who DOES exist in both LDAP and Redmine, but whenever he specifically sends an e-mail to Redmine, we get an "Unprocessable Entry" message in the logs:

Processing MailHandlerController#index (for <IP_ADDRESS> at 2010-01-26 09:17:24) [POST]
Session ID: b22225f66268e7b54a9bb06dbe5a5358 Parameters: {"unknown_user"=>"accept", "action"=>"index", "allow_override"=>"tracker", "controller"=>"mail_handler", "issue"=>{"project"=>"<PROJECT>", "tracker"=>"Support"}, "key"=>"<KEY>",......
.......
Completed in 0.01551 (64 reqs/sec) | Rendering: 0.00024 (1%) | DB: 0.00724 (46%) | 422 Unprocessable Entity [http://&lt;REDMINE_SERVER&gt;/mail_handler]

At first I had thought that maybe his e-mail syntax was off, but I have submitted the issue as both myself and another user and both time it went through and created the issue in Redmine.