We know some incompatible Addins. Most notably ESET.OutlookAddin in case we detect them, we should display a warning to avoid reports about empty mails. I don't see a way how we can be compatible with some of the Addins. For ESET it blocks our access via PropertyAccessor to any properties of the Mail.
In older versions we were more low level and might have not needed this because we accessed the properties through MAPI and not via OOM. But as we moved more and more to OOM to avoid accidental MAPI changes / syncs we need to access MAPI over the OOM view and that is the Property Accessor.
oomhelp.cpp:get_oom_object: failure: 'PropertyAccessor' p=00000000 vt=0 hr=0x80020009 argErr=0x0 dispid=0xfafd 11:59:56/8948/ERROR/oomhelp.cpp:put_pa_variant: Failed to look up property accessor.
^ This should be impossible, but ESET creates this situation.
We should show a warning for that instead of silently failing. I am adding gpgcom tag as customers of GnuPG VS-Desktop also had this issue.