Based on the provided reference, the High Risk Delivery Pool (HRDP) is a separate pool of outbound IP addresses, not a single specific IP address. Therefore, there isn't one exact HRDP IP address, but rather a collection of addresses used for a specific purpose.
Understanding the High Risk Delivery Pool (HRDP)
As defined in the reference, the High Risk Delivery Pool (HRDP) plays a crucial role within Exchange Online Protection (EOP).
Here's what the reference tells us about HRDP:
- It is a separate pool of outbound IP addresses.
- EOP uses this pool for routing outbound messages.
- The messages routed through HRDP are specifically those identified as spam emails.
This means that when Microsoft 365 detects an outgoing email as spam, it is sent out using an IP address from this designated pool, rather than the standard pool of IP addresses used for legitimate mail.
Why a "Pool" and Not a Single IP?
The use of a pool of IP addresses allows for better management and isolation of traffic. Sending identified spam through dedicated IP addresses helps to protect the reputation of the main outbound IP addresses used for delivering legitimate emails. If an IP address sending spam gets blocklisted by external mail systems, it affects only the high-risk pool, minimizing the impact on normal mail flow.
The specific IP addresses within the HRDP are managed by Microsoft and can change over time. The reference provided describes the purpose of HRDP but does not list the individual IP addresses that constitute the pool.
| Aspect | Description Based on Reference |
|---|---|
| What it is | A separate pool of outbound IP addresses |
| Who uses it | Exchange Online Protection (EOP) |
| What it's used for | Routing outbound messages identified as spam emails |
| Specific IP Address(es) | Not listed in the provided reference |
In summary, based on the reference, you cannot identify a single, exact HRDP IP address because it is defined as a pool of addresses used by EOP for sending out spam. The reference does not contain a list of these specific IP addresses.
