Iis – Using IIS smtp for incoming and outgoing and use hMailserver for mail accounts

I have installed hMailServer in one machine and IIS STMP in another machine. Even though hMailSever itself is a SMTP server.

I can't avoid this because the IIS SMTP server has some hooks which which encrypts and decrypts the incoming and outgoing mails.

Since IIS SMTP doesn't support to create & manage mail accounts, I thought of using hMail Server. Now I am able to send the outgoing mails by setting the SMTP relay settings in hMailServer. In this way If I send a mail to hMailServer's SMTP it relays to IIS SMTP server. This works fine.

But If I receive a mail from outside the mail directly goes to hMailServer. But the mails are encrypted. Ideally I should receive all mails to IIS SMTP then decrypt and send it to hMailServer so that the user can download the mails through POP3 to his outlook.

How do I do this please? Is there a option to transfer all incoming mails from IIS SMTP to send it to hMailServer. Please guide me how to achieve this.