What are some alternatives?
When comparing ApPHP Calendar and Apple Mail, you can also consider the following products
Teamweek - A project management software to help you get the best overview. Plan fast, change plans faster!
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Time Slot Booking Calendar PHP - Time Slots Booking Calendar PHP for online appointment booking and class scheduling.
Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
UpTo - Life goes beyond meetings and appointments
eM Client - eM Client is a Windows-based email client for sending and receiving emails, and managing calendars, contacts and tasks.