Not getting new emails pushed to Android

Not getting new emails pushed to Android

Hi there,

I recently set up my Zoho Mail account on my phone (Android 5.1, stock Email app, IMAP), but as of recently I'm not getting push notifications for new emails anymore, at least not with any consistency. Pulling to refresh within the app works correctly and shows new emails, and I can send emails from my phone just fine, but for whatever reason I've stopped getting emails pushed to my device, even though it was working when I very first set it up (about 3 weeks ago).

I've tried all sorts of combinations of settings with no luck. Currently I'm using the settings described here:

Incoming Settings
Username: myemail@mydomain.com
Server: imap.zoho.com
Port: 993
Security Type: SSL/TLS

Outgoing Settings
Username: same as incoming
Server: smtp.zoho.com
Port: 465
Security Type: SSL/TLS

Sync frequency is set to "Automatic (Push)", and I made sure that the Inbox folder is set to be synced.

Any ideas what could be wrong?

Thank you!