Cannot Delete or Move Emails from Printers - Error from emails with no body?

Question

Exchange 2010 SP2 (one mailserver for domain)
Outlook 2010
Outlook 2013
OWA
EAS
We have several Konica-Minolta MFPs on our network. Users regularly use the e-mail function to receive PDF scans.  These e-mails cannot be deleted in Outlook, OWA, or EAS.
I have tested this on multiple users, including myself.  The e-mails and attachments can be any size, starting at 50kb.  Other e-mails with PDF attachments behave normally--just not these. 
In Outlook 2010 I receive "The item cannot be deleted. It was either moved or already deleted, or access was denied."  I have verified with a MAPI viewer that these e-mails are sitting in the user's Inbox. 
OWA gives the same error message as Outlook 2010.
In Outlook 2013 I receive a similar error, and an Event Log notice:
Event 300
Microsoft Outlook Unknown Error
P1: 300032
P2: 15.0.4420.1017
P3: ajr8vP4: 0x80040119
Source: Microsoft Office 15 Alerts
These e-mails cannot be deleted. They cannot be moved to another folder. 
They can be Shift+Deleted.  They can be deleted via the MAPI viewer.  They can be opened, edited (Move > Actions > Edit Message) and if even one character is added to the body, after being saved they can be deleted as normal.
I have read many posts on TechNet and elsewhere:
A repair on the mailboxes does nothing. There are no PSTs.  This happens to even an empty mailbox, so size is not an issue. There are no host headers set in the bindings.  The IIS SSL Settings are ignoring Client Certificates. I have tested in Outlook
Safe Mode and without plugins. It is not Antivirus.
I have not reset the Virtual Directory, nor have I tested with a new Database.
I did find a solution: in all of the Konica-Minolta configurations, there was nothing set for a message body.  I think (but I am not sure) these e-mails were being sent without a body.
After I added text for the body, the emails behaved normally.
Is this an Exchange bug?  Is there something I can do to narrow the issue down, or adjust an Exchange setting so it doesn't happen again?
Thanks all!

Answer 1

Thank you for your reply, Fiona!
As I stated, I have examined the messages with a MAPI viewer. I did not notice any attributes that seemed out of order, except for the fact that the problem e-mails seem to lack a body:
Tag
Property Name
Konica: CAN'T Delete
Konica: CAN Delete
Normal Message
0x1000000A
PR_BODY 
Scan from Konica-BW
Err:Not Enough Memory
0x1013000A
PR_BODY_HTML 
Err:Not Enough Memory
0x10160003
PR_NATIVE_BODY_INFO  
0 (Undefined)
1 (Plaintext)
3 (HTML)
0x1009000A
PR_RTF_COMPRESSED 
Err:Not Enough Memory
Err:Not Enough Memory
0x0E1F000B
PR_RTF_IN_SYNC  
TRUE
TRUE
FALSE
I've compared the three e-mails. The "Konica: CAN Delete" is one from after I changed the Konica settings to include a message body (which was "Scan from Konica-BW").
My next planned steps are to speak to Konica, roll back RU6 and test, or just wait to see if MS releases a patch for the RU6 issue and see if it resolves my issue as well. 
If you have any further suggestions of things to look for, I am all ears. :)
Thanks again!