Policy
Change the limit for the number of MIME body parts
By default, the limit is 250 for the number of MIME body parts when an e-mail message is converted from MIME to MAPI. The number can be set to any positive integer. This helps prevent scenarios in which Outlook hangs while attempting conversion.
PackMicrosoft Office
CategoryMicrosoft Outlook 2016 / MIME to MAPI Conversion
Policy ID
645a33370efaInternal name
L_ChangelimitMIMEbodyRegistry
Copy registry mappings
HKCU\software\policies\microsoft\office\16.0\outlook\options\mail\mimebodiesPolicy notes
By default, the limit is 250 for the number of MIME body parts when an e-mail message is converted from MIME to MAPI. The number can be set to any positive integer. This helps prevent scenarios in which Outlook hangs while attempting conversion.