Do you have a predefined set of user proeprties or do you create them
dynamically based on some criteria/
Keep in mind that tehre is a 65,000 limit on the number of named proeprty
mappings per store.
Once you reach that limit, no new named proeprty can be created, no matter
whether you add it to the folder fields or not.

--
Dmitry Streblechenko (MVP)
http://www.dimastr.com/
OutlookSpy - Outlook, CDO
and MAPI Developer Tool
-
"Mark B" wrote in message
...
Thanks very much for all your help.

I went ahead and manually deleted the user defined fields from the Inbox
and SentItems folders and the errors stopped.

I think I'll amend the code so that if he programmatically creates new
user fields, the 3rd parameter is false so the folders don't store the
fields too.

I can't see any downside to this. Please feel free to correct this view if
you think I would need folder-based user-defined fields.


"Dmitry Streblechenko" wrote in message
...
I doubt that will help, not least if you are using Exchange: on the low
level, user proeprties are stored as named MAPI properties. To get a
property tag, Outlook calls IMessage::GetIDsFromNames passing the GUID
(PS_PUBLIC_STRING for the user properties) and id (the property name in
your case, can also be an integer).
Once a particular combination of GUID/id is mapped to a tag (4 bytes
int), it will always be used for that store (mailbox). The very first
time that tag is used when setting a property, the store will remember
the property type (PT_BOOLEAN, PT_SYSTIME, etc).
You cannot make the store forget about a particular property, once it is
used, the type cannot be changed.

--
Dmitry Streblechenko (MVP)
http://www.dimastr.com/
OutlookSpy - Outlook, CDO
and MAPI Developer Tool
-
"Mark B" wrote in message
...
My senior programmer whose work I am trying to debug decided that
whenever he wanted to add user property to a mail item, he would include
the third
parameter as True. That is, adding the user-defined field to the folder
as well.

Using the Outlook GUI just now I have seen a few user fields that have
Yes/No type in the "User-Defined Fields in Inbox" but for the particular
item, the field type is Date/Time. So there is inconsistency there.

I'm am guessing to remedy the whole thing I'll go through and delete all
user defined fields in all folders -- Inbox, Sent Items etc.

Then I am thinking to amend his code below labeled "//Create user
property if does not exist", making the third parameter False instead of
True.

Is there any downside to not having the user-defined fields mirrored in
the Folders?

Our code in other places does things like Advanced Search based on
user-defined field values.

I'd be interested to know best practice here -- it's for an Outlook 2007
VSTO C# Add-in for various different external clients.


"Dmitry Streblechenko" wrote in message
...
It ios not just on a particular message - themapping is on thestore
level,
plus you added the user property to teh folder props (thrird parameter
=
true).

--
Dmitry Streblechenko (MVP)
http://www.dimastr.com/
OutlookSpy - Outlook, CDO
and MAPI Developer Tool
-
"Mark B" wrote in message
...
The thing is I always get the error message:

'mail.UserProperties[propertyName]' is null

if I try to set its value though. Here's some immediate window
results:

?mail.UserProperties[propertyName] == null
true
mail.UserProperties.Add(propertyName, propType, true, Type.Missing)
'mail.UserProperties.Add(propertyName, propType, true, Type.Missing)'
threw an exception of type
'System.Runtime.InteropServices.COMException'
base {System.Runtime.InteropServices.ExternalException} : {"A custom
field with this name but a different data type already exists. Enter a
different name."}
mail.UserProperties[propertyName].Value = value;
'mail.UserProperties[propertyName]' is null
?mail.UserProperties[propertyName].GetType()
'((object)(mail.UserProperties[propertyName]))' is null
?mail.UserProperties[propertyName].IsUserProperty
'mail.UserProperties[propertyName]' is null
mail.UserProperties[propertyName].Value = 0;
'mail.UserProperties[propertyName]' is null




"Dmitry Streblechenko" wrote in message
...
I think this is as self-explanatory as it gets: you already have a
property with the same name but a different property type.
Once you used a particular type for any given name, you are stuck
with
that type.

--
Dmitry Streblechenko (MVP)
http://www.dimastr.com/
OutlookSpy - Outlook, CDO
and MAPI Developer Tool
-
"Mark B" wrote in message
...
VSTO C# Outlook 2007.

Does anyone know why I am getting the following exception from the
code
below and what the solution is?

"Exception while setting up user property:
A custom field with this name but a different data type already
exists.
Enter a different name.
Prop name = x-MYAPP-MyDate1
Value=21/11/2009 3:01:30 a.m.
Type = olDateTime"


private void SetProperty(string propertyName, object value,
Outlook.OlUserPropertyType propType)
{
try
{
//Create user property if does not exist
if (mail.UserProperties[propertyName] == null)
{
mail.UserProperties.Add(propertyName, propType,
true, Type.Missing);
}

//Set property value
if (value != null)
{
mail.UserProperties[propertyName].Value = value;
}
//Delete the property if value was null
else
{
mail.UserProperties[propertyName].Delete();
}
}
catch (Exception e)
{
string msg = "Exception while setting up user
property:\n" + e.Message + "\n"
+ "Prop name = " + propertyName + "\nValue=" +
value.ToString() + "\nType = " + propType;

MYAPP.LogMessage(msg);

}
}