When Microsoft throttles or Gmail diverts, you need a defensible diagnosis.

Reject rate

Shows how often providers reject a message immediately. It separates true acceptance failures from later placement or engagement issues.

Deferral / throttling rate

Shows how often providers delay, throttle, or temporarily defer delivery. That is often a reputation, volume, or rate-control signal rather than a final reject.

Hard bounce rate

Shows permanent undeliverability, for example because a recipient does not exist or a provider issues a hard refusal. It matters for list quality, data hygiene, and risk evaluation.

Inbox placement rate

Describes how often messages actually reach the inbox. This metric is not the same as technical acceptance or a high delivery rate.

Spam rate

Describes complaint and spam signals that providers directly use in reputation scoring. It influences acceptance, throttling, and inbox placement.

Authentication failures

Captures failures in SPF, DKIM, DMARC, or related checks. These failures can trigger acceptance issues, reputation loss, or incorrect security classification.

DMARC / DKIM / SPF alignment

Shows whether visible sender identity, return path, and signatures actually fit together. Formal configuration alone is not enough if alignment breaks in the real sending path.

Provider-specific error codes

Codes from Microsoft, Gmail, GMX/WEB.DE, and other providers help separate patterns cleanly. They show whether volume, reputation, policy, or authentication is the real cause.

Time to stabilize

Describes how long signals and behavior need to settle after a change. It shows whether a remediation is durable or only looks good for a short time.

Sending volume by domain, stream, and provider

A split by sending domain, use case, and destination provider shows where risk is actually created. Without that segmentation, local problems easily disappear inside aggregated reports.

Deliverability Audit

Review of authentication, infrastructure, reputation, sending patterns, list quality, and provider signals. The result is a technical assessment with a prioritized action plan for IT, CRM, and marketing.

Typical inputs

DNS records, sample headers, bounce logs, provider dashboards, routing details, sending volumes, and segmentation logic.

Result / output

Technical findings, risk assessment, prioritized actions, and a worklist split by platform, team, or stream.

Often useful when

Teams that need a reliable baseline before remediation, migration, scaling, or internal alignment.

Microsoft Incident Review

Analysis of Microsoft and Outlook issues such as 550 5.7.515, RP-001, RP-002, RP-003, deferrals, rate limits, SNDS/JMRP signals, and authentication paths.

Typical inputs

SMTP logs, sample headers, retry timing, SNDS and JMRP data, IP and domain inventory, and sending-path details.

Result / output

Incident review, root-cause hypotheses, validation steps, and a prioritized remediation sequence for Microsoft-specific failure modes.

Often useful when

Teams with acute Microsoft delivery problems, recurring throttling, or unexplained Outlook acceptance instability.

Gmail Compliance Check

Review of current Gmail bulk sender requirements: SPF, DKIM, DMARC, alignment, spam rate, one-click unsubscribe, unsubscribe processing, and problematic sending patterns.

Typical inputs

Headers, DNS records, complaint metrics, unsubscribe flow, campaign samples, and Gmail Postmaster or ESP reporting.

Result / output

Gap analysis against Gmail requirements, compliance risks, and a concrete remediation checklist for technical and operational changes.

Often useful when

Bulk senders, CRM teams, and operators who need to reduce Gmail risk before or after deliverability issues appear.

IP and Domain Warm-up

Ramp-up plan for new IPs, domains, streams, or ESP and MTA migrations. It accounts for providers, volume, engagement, pauses, segmentation, and warning signals.

Typical inputs

Target providers, expected volume, stream split, engagement data, domain plan, migration timeline, and sending constraints.

Result / output

Provider-aware ramp-up schedule, guardrails for pace changes, and decision criteria for pauses, rollbacks, or escalation.

Often useful when

Teams launching new infrastructure, moving providers, or separating transactional and marketing streams safely.

DMARC and Alignment Review

Review of SPF, DKIM, DMARC, Header From, Return-Path, DKIM d= domain, subdomain strategy, and policy risks.

Typical inputs

DNS records, sample headers from each stream, vendor inventory, forwarding scenarios, and current DMARC policy design.

Result / output

Alignment review, policy-risk assessment, and clear actions for DNS, signing, delegation, and stream ownership.

Often useful when

Organizations with multi-vendor sending, DMARC rollout plans, or recurring confusion around aligned identity.

Ongoing Monitoring

Definition and setup of monitoring for rejects, deferrals, hard bounces, spam rate, authentication failures, and provider-specific anomalies.

Typical inputs

Available logs, webhook or event sources, provider dashboards, ownership model, escalation paths, and current reporting gaps.

Result / output

Monitoring design, event taxonomy, threshold proposal, and an implementation-ready view of what to track and alert on.

Often useful when

Teams that want earlier detection of deliverability regressions and clearer operational ownership across systems.