New Mail Event does not work with some delegate mailboxes

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New Mail Event does not work with some delegate mailboxes
 
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wehbi




Posts: 82
Joined: 2013-10-31
Dear Add-In Express Team,

One of our customers is experiencing an issue where the "New Mail" event does not fire when using delegate mailboxes. What makes this particularly puzzling is that other delegate mailboxes on the same system are working as expected.

The following events are being used but are not triggered:

-public void adxOutlookEvents_NewMailEx(object sender, string entryIDCollection)
-public override void ItemAdd(object item, object sourceFolder)

The customer is running Exchange On-Premises version 0.20 (15.0.0.0) and the latest Outlook client.

Is there a known solution or recommended approach to resolve this issue?

Thank you in advance.

Best regards,
Birger
Posted 02 Dec, 2025 07:28:51 Top
Andrei Smolin


Add-in Express team


Posts: 19195
Joined: 2006-05-11
Hello Birger,

Find an example at https://www.add-in-express.com/creating-addins-blog/outlook-newmail-custom-solution/. It deals with the NewMail/NewMailEx events not occurring for some or all emails received. It also deals with the "emails received while Outlook was closed" scenario.

Regards from Poland (GMT+1),

Andrei Smolin
Add-in Express Team Leader
Posted 02 Dec, 2025 09:57:17 Top
wehbi




Posts: 82
Joined: 2013-10-31
Hello Andrei,

I’ve seen this approach before, but I’m wondering why it has been the recommended solution since 2011.
If this is still the only reliable method, I’ll take it into consideration — thank you!

We have plenty of customers who don’t experience this issue, so I’m trying to understand why.

I will test the approach in the next few days.

Regards,
Birger
Posted 03 Dec, 2025 08:33:03 Top
Andrei Smolin


Add-in Express team


Posts: 19195
Joined: 2006-05-11
Hello Birger,

wehbi writes:
We have plenty of customers who don’t experience this issue, so I’m trying to understand why.


I have no answer. I can guess your customers have different settings; don't ask me what these settings could be.

Irregularities with the NewMail (NewMailEx) event exist for quite a long time. Even if they are fixed you aren't guaranteed your customer runs a proper Outlook version with proper settings. The approach at that page is sort of a guarantee.

Also, it looks like no Outlook version triggers this event for emails that Exchange receives while your computer is turned off for the night.

Regards from Poland (GMT+1),

Andrei Smolin
Add-in Express Team Leader
Posted 04 Dec, 2025 15:05:48 Top