How do you diagnose reputation loss (Gmail Postmaster, SNDS)?

Diagnosing reputation problems requires checking multiple data sources.

Gmail Postmaster Tools:

• Domain reputation: High, Medium, Low, Bad
• IP reputation: Same scale for sending IPs
• Spam rate: Percentage reported as spam
• Authentication: SPF, DKIM, DMARC pass rates
• Requires minimum volume to show data

Microsoft SNDS (Smart Network Data Services):

• IP reputation scoring
• Trap hit data
• Complaint rates
• Filtering disposition
• Requires IP registration

Blocklist checks:

• Use MXToolbox or MultiRBL for comprehensive checks
• Check both domain and IP blocklists
• Spamhaus, Barracuda, Spamcop most impactful
• Some blocklists don't report publicly

Interpretation:

• Single signal may be temporary; patterns are concerning
• Cross-reference across multiple sources
• Compare to historical baseline
• Correlate with sending activity changes

Investigation questions:

• What changed before reputation dropped?
• Which campaigns or lists coincide with problems?
• Are issues isolated to specific mailbox providers?