We have an SBS2011 server which was handling POP3 email for one domain and Exchange email for the primary domain. We were using the POP3 connector for the POP3 account. We moved the POP3 account to Office365 and removed the POP3 accounts from the POP3 connector. We are having an issue with sending email from the new Office365 account to the primary account still on the Exchange server. Also, the users on the Exchange server cannot send mail to the users on the Office365 account.
What do I need to disable on the SBS side to resolve this issue? Will disabling the AD account for the Office365 users resolve? Can I just disable Exchange email for those users and still have them log into the domain?