@miles, you can try out Zoho Mail ( https://www.zoho.com/mail/zohomail-pricing.html ). We have free edition and also Trial option for Paid edition. You can even configure Split Delivery during evaluation wherein you can have some mailboxes hosted in Zoho and the rest in your existing mail system. Refer to https://www.zoho.com/mail/help/adminconsole/email-routing.ht... for detailed instructions. I have listed some of the articles which might be of interest to you :