The PUSH interval has been removed since version 9, you should use a fixed interval like 10 seconds or 1 minute.
When you add multiple Exchange or Office365 accounts using the real time connection (PUSH) you can face to a performance issue (delay to receive emails, slow connection, freeze), it is due to limitation of Microsoft API which enable by default 2 simultaneous connections to Exchange, we increased this limitation but performance goes down and depends on the computer you are running Automatic Email Manager...
To get a better performance we suggest you 2 solutions:
Solution 1: Instead of using PUSH, use an interval delay between each check
- For example 2 minutes, and more you add accounts in Automatic Email Manager more you need to increase this delay (for example if you have 5 Exchange/Office365 accounts you can set delay to 1 minute, if you have 20 accounts set it to 4 or 5 minutes for each account).
Solution 2: If PUSH is important for you
- You should change the type of account, instead of using an Office365 account use an IMAP4 connection (you can use existing preset for Office365 in IMAP like below).