Latency Probe

The probe command measures the time to establish an SMTP connection to a target domain from each outbound IP.

Basic Usage

# Probe from the default outbound IP
smtp-probe probe gmail.com

# Probe from every IP in the pool
smtp-probe probe gmail.com --pool

Output

Probing gmail.com (MX: gmail-smtp-in.l.google.com)

IP           Latency    Status
---          ---        ---
outbound     142ms      OK
1.2.3.4      87ms       OK
1.2.3.5      timeout    FAILED
1.2.3.6      203ms      OK

Use Cases

• IP health monitoring — Identify pool IPs with degraded connectivity
• Performance comparison — Choose the fastest outbound IP for a specific target region
• Pre-flight check — Verify IPs are reachable before deploying to production