The following table lists a number of commonly used MAPI methods and the circumstances under which they cause RPCs. To optimize your application’s performance, use the MAPI methods that cause the fewest RPCs.
Commonly Used MAPI Methods and RPCs
| MAPI Method | Causes RPC? |
|---|---|
| Advise | Never causes an RPC. |
| CompareEntryIDs | Very rarely causes an RPC. |
| CopyTo | Always causes an RPC. |
| CreateAttachment | Causes an RPC except when creating the first message and the MAPI_DEFERRED_ERRORS flag is set. |
| CreateBookmark | Causes an RPC except when creating a bookmark for the beginning or end of a table. |
| CreateFolder | Always causes an RPC. |
| CreateMessage | Causes an RPC except when MAPI_DEFERRED_ERRORS is is set. |
| DeleteProps | Causes an RPC for information store and folder objects, rarely for most other objects. |
| FindRow | Always causes an RPC, but retrieves extra information to save for subsequent calls of the QueryRows method, which can minimize future RPCs. |
| DeleteMessages | Always causes an RPC. |
| FreeBookmark | Never causes an RPC. |
| GetAttachmentTable | Causes an RPC except when MAPI_DEFERRED_ERRORS is set. |
| GetContentsTable | Causes an RPC except when MAPI_DEFERRED_ERRORS is set. |
| GetHierarchyTable | Causes an RPC except when MAPI_DEFERRED_ERRORS is set. |
| GetIDsFromNames | Usually causes an RPC unless the identifier is already in the cache (identifiers are cached locally after the first call). |
| GetNamesFromIDs | Usually causes an RPC, unless the name is already in the cache (names are cached locally after the first call). |
| GetProps | Causes an RPC unless properties are stored locally |
| GetRecipientTable | Causes an RPC except with MAPI_DEFERRED_ERRORS set. |
| GetRowCount | Usually causes an RPC, except when table properties are cached by provider. |
| OpenEntry | Causes an RPC except with MAPI_DEFERRED_ERRORS set. |
| OpenMsgStore | Always causes an RPC. |
| OpenProperty | Depends on the property. Never causes an RPC if MAPI_DEFERRED_ERRORS is set. |
| QueryColumnsAll | Causes an RPC for contents, attachment, and recipient tables. Never causes an RPC for all other tables. |
| QueryPosition | Usually causes an RPC, with a few exceptions (such as at the beginning and end of a table). |
| QueryRows | Usually causes an RPC. Never causes an RPC when used after FindRow (on same row) or when already at end of table. |
| QuerySortOrder | Never causes an RPC. |
| Release | Causes an RPC only for an information store object. Never causes an RPC for all other objects. |
| Restrict | Causes an RPC only if called before data is in the cache. Does not when passed NULL on already nonrestricted table. |
| SaveChanges | Causes an RPC except with MAPI_DEFERRED_ERRORS set, although using MAPI_DEFERRED_ERRORS is not usually recommended. |
| SeekRow | Usually causes an RPC except when already at the row, seeking to the end, or seeking to the beginning. |
| SetColumns | Causes an RPC only if called before data is in cache. |
| SetProps | Causes an RPC for information store and folder objects, rarely for most other objects. |
| SortTable | Causes an RPC only if called before data is in the cache. |
| SubmitMessage | Always causes an RPC. |