Server push completely relies on the client being responsive. I used MailForExchange on E61 myself for a while and over time the client does appear to simply "forget" to Ping the server.
In order for push to work, the client must:
1) Send a "Ping" request to server whenever a previous "Sync" finishes,
2) Perform a "Sync" whenever server responds to indicate new data available,
3) Send a "Ping" whenever server responds the previous "Ping" with no new data,
4) Send a "Ping" after timeout
I have found that E61 eventually, sometime long sometimes short, always "forgets" to do one of the above and effectively breaks the push mechanism. To bring it back on track, I had to do a manual sync and push may work for a while until it breaks again later.
In sync.log, you should see the Ping requests and Ping responses as regular as heartbeat when the client is behaving correctly.
Hope this helps explaining the issue. Thanks! |