When trying to create an IMAP Mailbox Sync via Office 365 , I was getting the following Failed Error next to the Sync Status

TLS negotiation failed with status AlgorithmMismatch

The IMAP Server I was syncing from was using SSL  on port 993 however the SSL cert was self signed rather than from a proper cert authority

In the end I had to enable syncing through 143 Uncrypted or you can purchase a sign SSL cert for the migration