You can setup something substantially similar with the new system which works arguably better that the old Solve360.
The recommended approach to consolidate mailboxes is to Forward messages from your other email providers instead of using the “POP” feature previously provided. This forces immediate delivery of email to your account (no extra step, no waiting, no batch processing) and reduces the possibility of the other provider triggering interruptions e.g. quota exceeded, problem with their POP service etc (man-in-the-middle causing problems which are difficult for clients to troubleshoot).
Under Settings, Sending tab, Email Identities you can setup a profile for each of your email accounts to send messages using different email addresses (email identities).