When encrypted email with attachments were sent to Exchange users from Domino via CMN the attachments would not get processed. They would come across all garbled and unreadable. This issue only effected encrypted email with attachments. Normal encrypted email came across just fine.
On some occasions the attachment was missing or empty.
This issue is cause by a code defect in the Domino server and effects version up to and including 8.5.2
There is a SPR logged with IBM and it has been addressed in Domino 8.5.3
https://www-304.ibm.com/support/docview.wss?uid=swg1LO53452
• This APAR is associated with SPR# JCAR87LH7L.
• Fixed in 8.5.3
This issue is not fixed in 8.5.2 HF3