Some Emails problems after plesk 10.2.0 upgrade!

[m0rpheu5]

i´m getting problems with one client after the Plesk was upgrade from 9.5.0 to 10.2.0, he has on email group by using one normal email account with multi email forwarding, some emails that some users sent to this email group return with error in the subject like "Error Message NO.0429" and "Error Message NO.0406"

in the "Error Message NO.0429" comes with this message:

This E-mail was sent from "RNPC266FC" (Aficio MP 3500).
Queries to: myclients@email.com
**************** Error Report( 2011. 6.24 15:47 ) ****************
Sender: myclients@email.com
Error Type: Invalid File (Code Error)
Please Confirm
Thank You

and the "Error Message NO.0406" comes with this message:

This E-mail was sent from "RNPC266FC" (Aficio MP 3500).
Queries to: expert-log@expert-log.com
**************** Error Report( 2011. 6.22 15:10 ) ****************
Sender: expert-log@expert-log.com
Error Type: Invalid File (Code Error)
Please Confirm
Thank You

What could be? How can i fix this? My client is always asking me about this error, and he wants to fix it.

Thanks