MAPI Requests - Exchange Server (TCP/RPC) vs IMAP-Connection

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I am currently developing an Outlook VSTO-AddIn using C#. I want to read certain attributes of each mailItem. (E.g. SenderName, SenderEmailAdress, etc. .. ) As far as I have understood I have understood- I have two option for achieving this:

  1. Accessing the Outlook object model
  2. Using a "Property Accessor Object" to read a MAPI property that belongs to a MailItem but that is not exposed in the Outlook object model. (https://docs.microsoft.com/de-de/office/vba/api/outlook.propertyaccessor)

A little Code Snippet for the property accessor: The mailItem is an object of the MailItemClass Class from the Microsoft.Office.Interop.Outlook namespace.

PropertyAccessor olPA = mailItem.PropertyAccessor;
SenderMailAddress = olPA.GetProperty("http://schemas.microsoft.com/mapi/proptag/0x0C1F001F");

I am encountering the following strange behavior: The results differ depending on whether I access the mailbox via IMAP or via TCP/RPC-Connections. Primarily when trying to access attributes of a mailItem sent by someone, whose Account has been removed. With an IMAP Connection the MAPI-Requests work fine, with TCP/RPC they don't.

Most resources I find on that topic are from 2009-2010, so I am unsure how they translate to the 2016-Version of Outlook.

Any hints that shed light on the difference between TCP/RPC in that case are greatly appreciated.

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c#outlookvstoimapmapi

1 Answers

1
votes

There is really no distinction between the two: PR_SENDER_EMAIL_ADDRESS gets retrieved by both MailItem.SenderEmailAddress and by MailItem.PropertyAccessor.GetProperty.

Do you actually see the PR_SENDER_EMAIL_ADDRESS property when you look at the item with OutlookSpy or MFCMAPI?