Bulk complaint level (BCL)
Microsoft assigns a bulk complaint level (BCL) to inbound messages from bulk mailers. A higher BCL indicates a bulk message is more likely to generate complaints (and is therefore more likely to be spam).
| BCL Value | Description |
|---|---|
| 0 | The message isn't from a bulk sender. |
| 1, 2, 3 | The message is from a bulk sender that generates few complaints. |
| 4, 5, 6, 7* | The message is from a bulk sender that generates a mixed number of complaints. |
| 8, 9 | The message is from a bulk sender that generates a high number of complaints. |
| * This is the default threshold value used in anti-spam policies. | |
For more information, see Bulk complaint level (BCL).