| Platform SDK: SMTP Server Events |
[This is preliminary documentation and subject to change.]
Increment the MailMsg object's usage count.
HRESULT AddUsage();
| Value | Description |
|---|---|
| S_OK | Success. The usage count incremented from zero to one. |
| S_FALSE | Success. The usage count is already above 1. |
| E_FAIL | Failure. The usage count was negative. |
When the usage count is non-zero, the MailMsg object's resources are more likely to be kept cached in memory.