Sophos Email and Pop3-SMTP-IMAP

Hi.

[BACKGROUND]
- Email hosted with 3rd party offering POP3, SMTP and IMAP (Mail server is not Exchange)
- Subscribed to Sophos Central, did all necessary configuration [FOR INBOUND ONLY, NO OUTBOUND] on Email Security. Inbound Destination set to domain with port 995

[Issue]
- Email reached Sophos Central, log shown Delivery Failed or Queued for Delivery for INBOUND emails (email unable to reach email server on our 3rd party email hosting)

I've went into cPanel, but found nothing much to configure EXCEPT to WHITELIST Sophos Delivery IP in SPAM Filter (this is the only place i can add in Sophos Delivery IP in cPanel) and our email hosting company (3rd party) told us that they did not blocked any IP address listed in Sophos Delivery IP.

[My Questions]
- I would like to know that, will Sophos Central Email support hosting that ONLY support POP3, SMTP and IMAP? Rather than EXCHANGE/GMAIL/O365?
- IF POP3, SMTP and IMAP is supported with Sophos Central Email, what is the additional steps that i need to take into account to let emails that stuck in Sophos Central Email to deliver to our 3rd party email hosting's email server?