Most of us know the ongoing problems with Apple MacOS Mac Mail and their improper use of the IDLE command. Instead of reusing an open connection they will continuously reopen new connections until the Mail Server runs out of available IMAP Ports or they trigger IDS Rules and get blocked (many of our MacOS customers trigger 60+ IMAP connections in just a 1 minute span). For the past 7+ years the solution has always been to disable IDLE in Mac Mail. That is until MacOS Sierra which recently removed this option from the end-user!
For the time being we have begun suggesting to our Mac customers that they use EWS instead of IMAP, however this is only a viable option if they maintain < 5000 messages in their Folders and there are currently issues with EWS on MacOS as well (Contacts specifically).
Other than disabling IDLE in SmarterMail entirely does anyone know how to disable IDLE in MacOS Sierra?