Office 365 with external SMTP server

AnnTaeYoun 

My original thought was to fully integrate everything into Office 365. The old company domain will primarily be used for sending and receiving emails for the time being, and unfortunately, migrating this domain to Office 365 is not an option. That's why I'm setting up everything in Office 365 with this new company domain, e.g., email address removed for privacy reasons, and the users will log in everywhere using this account. Even when I send documents to customers, the link will include the Firmaneu.ch domain.

Of course, I could create an Outlook profile with the Firmaneu.ch domain and add the old mailbox via SMTP/POP, but then I would lose many of the functions that the new Office 365 provides, and I would have to configure the mailbox on every device (tablet, mobile phone, etc.).

That's why I would prefer if Office 365 could retrieve emails from the POP server and deliver them to the mailboxes, and when I send an email, Office 365 sends it to the old SMTP server, which then sends it under the old domain.

Is there anything I can do to achieve this?

Best regards,
Damian