internetHeaders for Appointments

[DanilKorotenko]

Related issue: #4388.

If I obtain Appointment via EWS with GetItem command and IncludeMimeContent flag on, I definitely can see internet headers in the mime content.

If someone send me invitation to event, I recieve an email with internet headers.

How can I add my custom internet headers to this process?

I mean:

1. User with my addin create an appointment.
2. My addin add custom information to that appointment.
3. User send invitation to that apoointment to another user
4. Another user open this appointment
5. My addin on other user side read the custom information.

How I can implement this scenario?

Content: Get and set internet headers - Office Add-ins
Content Source: docs/outlook/internet-headers.md
Service: outlook
Sub-service: add-ins

Describe your scenario
What is the problem to solve?

Which APIs or add-in features?
What should be showcased in the sample? Are there features that need samples to better understand how to use them in add-ins?

[DanilKorotenko]

Additional info:
https://learn.microsoft.com/en-us/exchange/client-developer/web-service-reference/extendedfielduri

What ExtendedField is for?
Example XML shows how to set custom property. Ok. But what is next? Can this custom property go outside? For example, if I set custom property to appointment, and send invitation to it to other user. Can that user read that custom property with my addin? What practical use of extended fields?

[AlexJerabek]

Thanks for raising this issue @DanilKorotenko. @ElizabethSamuel-MSFT, could you please take a look?

[DanilKorotenko]

Post on Microsoft 365 Developer Platform Tech Community:

https://techcommunity.microsoft.com/t5/microsoft-365-developer-platform/add-the-internetheaders-property-to-the-office/idi-p/3660816

[ElizabethSamuel-MSFT]

@DanilKorotenko I'm checking with the feature crew to see if there's an EWS workaround.