I have been using airmail for several months to manage 4 email accounts. All accounts were either gmail, exchange or outlook based. My daily email volume was very heavy and I was able to much more easily manage all accounts, archive and file emails and retrieve all emails on demand. I needed to add yet another account which was NOT from one of the major email servers. It was easily added and then imported using iCloud to my other devices ( Iphone and Macbook pros). However, I was not getting consistent synching across all devices for every action - this had never happened before and I sent a note to customer support. Within 10 minutes, I had the answer from Sarah from customer support and was able to reconfigure my server settings within a matter of minutes with her guidance. All is working great and I continue to be a big fan of both the application which is very robust and now the customer support team!
Jim Wambach about Airmail - Your Mail With You, v1.6.7