Invalid Named Property

We call the microsoft exchange to set the extended property which in our case is an unique guid

microsoft.exchange.webservices.data.core.exception.service.remote.ServiceResponseException: An internal server error occurred. The operation failed., Invalid named property

Its been working great until now when some of our users are facing the above issue ....

 val uId = getUniqueId();    

val emailExtendedPropDef = new ExtendedPropertyDefinition(uId,"uniqueId", MapiPropertyType.String)
    try {
      email.setExtendedProperty(emailExtendedPropDef, uId.toString)
      email.sendAndSaveCopy()
    } catch {
      case e: Exception =>
        error(s"Exception in setting extended property for user $from", e)
        throw e
    }

trying to find the root cause of the issue, we are also thinking it might be related to throttling on Microsoft exchange for extended properties (Not sure how to prove if it's indeed throttling) any help to point us in the right direction will be of great help

Our use case is to able to retrieve the email when customer want's to reply back we want to retrieve that particular email to be included in users reply....currently we are using the uid to achieve that ....

we have been using the code as per the documentation here

https://docs.microsoft.com/en-us/previous-versions/office/developer/exchange-server-2010/dd633654(v%3Dexchg.80)

and also the documentation here

https://github.com/OfficeDev/ews-java-api/wiki/Getting-Started-Guide#extended-properties

Update : As per the comments we do understand that we have to treat extendedProperty as a column definition and update the same column ...but we couldn't figure out how to achieve this as...Any code samples to point us in the right direction will be of great help

Latest Update : We have deleted some of the extendedPropertyDefinition's but still facing the same invalid property could some one please point us in the right direction

Is it safe to say that getUniqueId returns a different guid on each call? If so, then that is the problem. Think of the Guid for an extended prop as a namespace. The exchange store limits the number of custom extended props to something like 32k per mailbox. So you are likely hitting that limit. But aside from that, the main reason for creating an extended property is so that you can refer to it later. But if you are basically discarding the namespace each time, you are leaving orphaned props on items. Without understanding your particular scenario, I can only say that the Guid should be thought of truly as a namespace. Choose one for your app/company/scenario and hard code it. They create all the named props you want within that namespace. For instance, "MyProp/String" in Guid namespace 1 is a different property than "MyProp/String" in Guid namespace 2.