One-Off Entry Identifiers
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One-Off Entry Identifiers

Last modified: July 23, 2011

Applies to: Outlook

One-off entry identifiers are created by MAPI in the IAddrBook::CreateOneOff method and by components that do not have access to the MAPI subsystem, such as gateway components. For more information, see IAddrBook::CreateOneOff. The following illustration shows the format of a one-off entry identifier.

One-off entry identifier format

One-off entry identifier format

The first field is a special MAPIUID structure that identifies the entry identifier as representing a custom recipient. This MAPIUID structure must be set to the constant MAPI_ONE_OFF_UID. MAPI_ONE_OFF_UID is defined in the header file MAPIDEFS.H.

The version and flags fields are 16-bit words in Intel byte order. The version field must be set to zero. The flags field can be set to the following values:



The MAPI_ONE_OFF_NO_RICH_INFO flag is set if a recipient should not receive message content in the Transport Neutral Encapsulation Format (TNEF). This flag is set when MAPI_SEND_NO_RICH_INFO is passed to IAddrBook::CreateOneOff method.

The MAPI_ONE_OFF_UNICODE flag is set if the display name and e-mail address are Unicode strings. This flag is set when the MAPI_UNICODE is passed to IAddrBook::CreateOneOff. When the MAPI_UNICODE flag is not passed to CreateOneOff, MAPI assumes that the display name and e-mail address strings are in the workstation's current ANSI character set. ANSI strings generally do not work well in messages that are sent between platforms using different character sets because the code page is not encoded in the entry identifier. To protect against this potential incompatibility, many address types are limited to only those characters that are common across multiple character sets. However, to ensure character set and platform compatibility, clients should use Unicode for the character strings in their messages.

The display name is a null-terminated string that corresponds to the recipient's PR_DISPLAY_NAME (PidTagDisplayName) property and to the lpszName parameter passed to IAddrBook::CreateOneOff. The character set is Unicode if the MAPI_ONE_OFF_UNICODE flag is set and ANSI if it is clear.

The address type is a null-terminated string that corresponds to the recipient's PR_ADDRTYPE (PidTagAddressType) property and to the lpszAdrType parameter passed to IAddrBook::CreateOneOff.

The e-mail address is a null-terminated string that corresponds to the recipient's PR_EMAIL_ADDRESS (PidTagEmailAddress) property and to the lpszAddress parameter passed to IAddrBook::CreateOneOff.

Note Note

There is no padding in one-off entry identifier structures; the bytes are packed exactly as indicated above and the entry identifier length should not include any bytes beyond the terminating null character of the e-mail address.

Clients and address book providers that manually construct one-off entry identifiers might also need to generate values for the PR_RECORD_KEY (PidTagRecordKey) and PR_SEARCH_KEY (PidTagSearchKey) properties. The record key is identical to the entry identifier. The search key should be formed by concatenating the following fields in the following order:

  1. The address type, converted to uppercase characters.

  2. A colon (:).

  3. The e-mail address, converted to uppercase characters.

  4. A terminating null character.

No character set conversion must be done when generating the search key.

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