Creating new email via MAPI doesn't include multiple recipients

A customer of ours is using EMC for their IMAP account and it’s been working fine up until recently. Their main invoicing application is using MAPI to generate emails with the attachment and body pre-filled, but it only accepts the first recipient in the list, not all of them. Emails still send fine, and we can manually add the extra recipients but that’s obviously not ideal.

v8.2.1659 (845a639)