Our software does not allow for users to sync POP email accounts. This is because of a limitation to those types of emails. With POP accounts, an email cannot exist and be accessible in two different places. With IMAP and Exchange accounts, an email can reside within multiple locations.
You can still utilize your POP email address as your username and send emails in Engage from that address. This approach does not sync this account to Engage, and there are limitations to certain features in Engage if you do not use a synced account. However, you will still be able to access most benefits of the software. For more information on synced and non-synced accounts, check out our support article titled, "What is the difference between a synced and non-synced account in Engage?".