Do old Exchange-2013 Servers support modern office addin schemas? - outlook

Question

I have been browsing through the internet looking for some answers on my question. Basically, we are developing several Office/Outlook addins. And each addin type is installed via their manifests.
In modern systems, the following schema is used in their manifest :
<OfficeApp xmlns="http://schemas.microsoft.com/office/appforoffice/1.1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:bt="http://schemas.microsoft.com/office/officeappbasictypes/1.0"
xmlns:mailappor="http://schemas.microsoft.com/office/mailappversionoverrides/1.0" xsi:type="MailApp">
For older systems, we are using :
<OfficeApp xmlns="http://schemas.microsoft.com/office/appforoffice/1.1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="MailApp">
I was wondering, if older systems will have problems if I use the newer schema on them.
In short, does Exchange 2013 support this schema declaration? :
<<OfficeApp xmlns="http://schemas.microsoft.com/office/appforoffice/1.1"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:bt="http://schemas.microsoft.com/office/officeappbasictypes/1.0"
xmlns:mailappor="http://schemas.microsoft.com/office/mailappversionoverrides/1.0" xsi:type="MailApp">
Thank you.

Answer 1

The manifest with mailappversionoverrides should install on recent CU's for Exchange 2013 because of how the schema is defined in Exchange 2013. However, Exchange 2013 does not have logic to use or validate recent the more recent schemas added to the manifests. This means, for example, Exchange 2013 does not validate the new nodes, and OWA from Exchange 2013 will not make use of the new additions in the manifest. On the other hand, recent Outlook connecting to Exchange 2013 should be able to retrieve full manifest.
Keep in mind that some features and API require both Exchange and Outlook support, so those features would not work with Exchange 2013.
Also for reference on Exchange 2013 lifecycle: https://techcommunity.microsoft.com/t5/exchange-team-blog/exchange-server-2013-enters-extended-support-lifecycle-phase/ba-p/607811#:~:text=Exchange%20Server%202013%20enters%20the%20Extended%20Support%20phase,product%20updates%20due%20to%20time%20zone%20definition%20changes.