For the past year or so we've been running a Windows service that is responsible for reading emails from one Exchange 2010 SP1 mailbox. We do this with a streaming subscription. Initially, we were hard coding our Exchange server as the EWS URL (https://email.company.com/EWS/Exchange.asmx) and all was working pretty well in regards to streaming notifications.
We later read online that it was good practice to use autodiscover instead of using hard coded values. Which makes sense so we implemented that small change. A few weeks later we realized that about 25% of the time we simply weren't receiving streaming notifications when there was mailbox activity. It wasn't a huge deal because we were syncing every 15 minutes so no emails were lost. It simply meant that we would read them later.
For some reason there are instances where an autodiscovered EWS URL will fail to send streaming notifications for days at a time. This is a problem because we're now almost solely relying on syncing on a timer, which makes utilizing a streaming subscription pretty redundant.
After we realized this, we set the url back to Exchanges server EWS URL (https://email.company.com/EWS/Exchange.asmx). All appears to be working again. Although manually setting the URL works fine, we would like to begin using autodiscover again.
Also, I have tested the autodiscover tester that comes with Outlook 2010 and both URLs match.
Lastly, we have tried using the `AutodiscoverService` class as well as the `Autodiscover` method from the `ExchangeService` class with no differences.
What is the reason for this?
Any ideas?