Maximum IMAP accounts in Outlook

[twinbytes]

What is the Maximum number of IMAP accounts Outlook can successfully support in Outlook 2010 and 2016?  I have a couple computers and one of them has 15 IMAP accounts and 3 accounts now are not receiving emails in the Inbox.  We tried deleting the OST file, recreating the account and ensuring no filters in place.  It syncs the Sent Items no problem but nothing in the Inbox and so I'm thinking maybe we are pushing the limits of Outlook but I can't find documentation on this anywhere.

Can someone please confirm what the limits are for IMAP?