Send calendar invitation using PHP

> Background I have various small PHP tools that send calendar invitations it works all good for up to Outlook 2016 but if invitations are sent to Office 365 (Outlook 2016) they arrive as .ics attachment and person have to open the attachment to add to their calendar. So I need someone to send me a block of code that will use PHPMailer to email the calendar invitation and they should appear in Outlook 2016 as as well as normal invitation with Accept Reject option. You need to write your own example code the way you like. I will not provide my working copy of code. > Requirements * write in PHP, without using any php frameworks * should use PHPMailer to email the calendar invitations * invitation should arrive at Outlook with Accept Rejection option not as an .ics attachment