Email deliverability checklist

Authentication: SPF, DKIM, and DMARC

Start with DNS because unauthenticated mail faces harsh filtering regardless of template quality. SPF publishes which servers may send for your domain. DKIM signs messages cryptographically. DMARC tells receivers how to handle failures and where to send reports.

Use MailFleet free SPF, DKIM, and DMARC checker tools before large sends. Confirm SPF lookup count stays under ten includes to avoid permanent errors. Verify the DKIM selector in DNS matches your provider active signing key. Set DMARC policy appropriate to your maturity — often p=none during monitoring, tightening only when passes are consistent.

Alignment matters: the From domain seen by recipients should align with SPF and DKIM domains per DMARC rules. Misalignment produces passes on individual protocols but DMARC failures overall.

• SPF record published and includes correct sending IPs or provider mechanisms
• DKIM selector resolvable; signing active on outbound mail
• DMARC record present with monitored policy and reporting mailbox
• Return-Path or bounce domain aligned where provider supports custom domains

Infrastructure checks beyond DNS

Run MX lookup to confirm mail routing for your domain is intentional. Use reverse DNS checker on sending IP — generic cloud hostnames on marketing domains raise policy flags on strict receivers.

Domain email health check aggregates multiple signals into one pre-send review. Fix blocklist appearances before campaigns when tools report listings.

TLS configuration on SMTP submission must match provider requirements. SMTP diagnostics validates connection, STARTTLS or SSL, and AUTH before you save profiles in MailFleet.

Permission-based list verification

MailFleet is for permission-based sending only. Every address should have documented consent or another lawful basis recognized by your counsel. Purchased, scraped, harvested, or recycled lists fail this checklist immediately — do not proceed.

Verify import files for duplicates, role addresses where inappropriate, and obvious typos. Segment by signup source and date so engagement strategies respect how each group opted in.

Suppression lists must be current: unsubscribes, hard bounces, complaint addresses, and contractual do-not-mail entries merged before import.

List hygiene and bounce management

Remove hard bounces from active segments before new campaigns. MailFleet logs identify 5.1.1 and similar codes for suppression.

Reactivation campaigns to dormant permission-based users need lower volume and careful monitoring — not full-list blasts. Complaint rates spike when recipients forgot they subscribed.

Role accounts (info@, sales@) behave differently than personal inboxes. Market to them only when consent explicitly covers those addresses.

Sender identity and legal footer requirements

From name and address must honestly identify the sender. Deceptive subjects or disguised identities violate MailFleet anti-spam policy and CAN-SPAM expectations.

Include physical mailing address where CAN-SPAM applies. Marketing mail needs a working unsubscribe mechanism — one-click where standards require it.

Match Reply-To to a monitored mailbox. Broken reply paths increase complaints when recipients cannot opt out through response.

Content review and SpamAssassin pre-check

Run integrated MailFleet SpamAssassin checks on subject, HTML, plain text, and headers before send. Fix triggered rules: link density, spammy phrases, missing text/plain alternative, suspicious URLs.

Balance images and text; avoid URL shorteners that appear on blocklists; use reputable HTTPS links. Test rendering on mobile because broken HTML sometimes correlates with filtering.

SpamAssassin score is one signal, not gospel. Use it to catch obvious issues; pair with authentication and list quality for real-world readiness.

Template technical headers

List-Unsubscribe headers support one-click unsubscribe on capable mailbox providers. They reduce complaints when implemented correctly alongside visible footer links.

Precedence and auto-response headers should be correct for transactional versus marketing classes — mislabeling confuses filters and users.

From, Date, Message-ID, and MIME structure should be valid. Email header analyzer on received test messages helps validate what actually left your provider.

Provider configuration in MailFleet

Confirm correct provider profile: host, port, TLS mode, credentials, and verified From identities. Test connection in app and via SMTP diagnostics after any credential rotation.

Check provider dashboard for quota remaining, sandbox mode, domain verification status, and account flags. API and SMTP limits differ.

Document proxy usage if applicable; proxies change egress IP which affects SPF alignment unless providers handle it.

Capacity and pacing plan

Review MailFleet capacity scoring for planned volume relative to domain age and history. Set daily ceilings below provider maximum on new infrastructure.

Schedule large permission-based campaigns in batches with monitoring between days. Warm-up applies after pauses, new domains, and dedicated IP assignment.

Define internal abort thresholds: bounce rate, deferral rate, complaint rate that triggers pause. Logs and webhooks support enforcement.

Pilot send and seed inboxes

Send a pilot batch to engaged recipients and seed inboxes you control across major providers before full scale. Review logs within hours, not days.

Compare pilot SpamAssassin results to production template — last-minute edits bypassing checks are a common failure mode.

Inbox placement seed tests complement SMTP success. Handoff can succeed while mail lands in spam; adjust content and authentication if seeds show filtering.

Monitoring and post-send review

Configure MailFleet webhooks or export schedule for production campaigns. Alert on bounce spikes during multi-day sends.

Review campaign reports after completion: totals, bounces, deferrals, trends versus prior campaigns. Investigate anomalies before the next send.

Update suppression files and internal runbooks with lessons learned. Deliverability checklist is a loop, not a one-time PDF.

Enterprise and procurement alignment

Security reviewers often ask for authentication evidence, permission policies, and data handling. MailFleet security documentation and this checklist support those conversations without overstating certifications.

Align checklist completion with client sign-off on list sources and send schedule. Agencies reduce liability when clients acknowledge consent responsibility in writing.

Linux teams: use official DEB or RPM packages on x86_64 or ARM64 — AppImage is not distributed. Same checklist applies on all platforms.

What this checklist cannot guarantee

No checklist guarantees inbox placement. Receivers use engagement, reputation, and proprietary signals beyond your control. The checklist eliminates avoidable self-inflicted failures.

MailFleet licenses at pay.mailfleet.app/buy/1year ($49) and pay.mailfleet.app/buy/lifetime ($79) provide software capability — not shared sending reputation or legal compliance by default.

Responsible bulk email means honest identity, working unsubscribes, and permission-based lists. Checklist items assume that foundation; without it, stop and fix consent before technical optimization.

Transactional versus marketing classification

Not every message is marketing. Password resets, order confirmations, and account alerts may qualify as transactional with different footer and consent rules depending on jurisdiction. Misclassifying promotional content as transactional to avoid unsubscribe requirements is a compliance violation and a deliverability risk when recipients complain.

When a single MailFleet template mixes unrelated promotions with receipts, filters and users both penalize you. Separate streams: transactional provider profiles and templates for operational mail; marketing profiles with full unsubscribe and List-Unsubscribe headers for campaigns. The checklist applies fully to marketing sends; transactional sends still need authentication and accurate identity.

Document classification decisions with legal input. Procurement reviewers sometimes ask whether MailFleet sends marketing or operational mail — the answer depends on your content and consent, not the software brand.

International and multi-brand considerations

Multi-brand agencies must run the checklist per domain and per client list source. Shared provider credentials across brands without isolation can spread reputation damage. MailFleet multiple provider profiles help, but DNS and suppression must also stay brand-scoped.

International sends add GDPR, CASL, ePrivacy, and local anti-spam rules. A checklist item valid in the US may be insufficient in Germany or Canada. Translate unsubscribe and consent flows where required; do not assume English footers cover EU recipients.

Time zone and holiday awareness affect engagement, not just scheduling convenience. A checklist signed off Friday for Monday send should re-verify DNS if IT rotated keys over the weekend — automation without re-check assumes infrastructure stasis that rarely holds.

Feedback loops and post-send signals

After send, monitor complaint feedback loops where providers offer them, Gmail Postmaster Tools for domain reputation trends, and Microsoft SNDS for IP data when applicable. MailFleet logs show bounces; feedback loops show complaints that never bounced.

Low open rates are not a checklist item but inform future segmentation. Permission-based lists with zero engagement over twelve months should be sunset or re-permissioned before the next checklist cycle — not mailed repeatedly because authentication passed.

Close the loop: checklist failures discovered post-send become new mandatory items. If pilot showed unexpected Gmail deferrals, add Gmail seed review to every future checklist for that domain until metrics stabilize.

Checklist sign-off and stakeholder roles

Assign owners: marketing owns content and unsubscribe copy, engineering owns DNS and provider profiles, legal owns consent classification, operations owns MailFleet send execution and log monitoring. Checklist items without owners get skipped under deadline pressure.

Use a written sign-off for campaigns above defined volume thresholds. Sign-off captures date, DNS check results, SpamAssassin outcome, capacity plan, and named approver. Agencies protect themselves when clients later dispute send decisions.

MailFleet desktop workflow supports this governance without a cloud approval product — export check results from DNS tools and SpamAssassin screens into your ticket or document store. Evidence matters more than checkbox software.

Annual and quarterly checklist maintenance

Review checklist quarterly against provider rule changes, new regulations, and lessons from incident retrospectives. Add items when DKIM rotation caused an outage; remove items that no longer apply when you standardize on a provider feature.

Annual training refresh for anyone with MailFleet send access. Responsible sending policy updates from MailFleet anti-spam and acceptable use pages should be circulated with checklist changes.

Enterprise procurement may request checklist documentation during renewal. Keep a version history with dates so reviewers see continuous improvement rather than a static PDF from two years ago.

Pre-send review for HTML and accessibility

Broken HTML and missing alt text hurt accessibility and can trigger filtering when tags are malformed. Validate rendering in mainstream clients before pilot. MailFleet SpamAssassin catches some markup issues; manual preview catches layout breaks that affect trust when recipients open on mobile.

Link URLs should use HTTPS and resolve to expected destinations. Redirect chains through suspicious domains score poorly. UTM parameters are fine when the landing domain matches brand expectations.

Plain-text part should convey the same offer and unsubscribe path as HTML. MIME mismatches confuse filters and screen readers. Checklist includes content parity, not only marketing copy approval.

Attachment and image policy

Large attachments increase rejection risk and hurt mobile recipients. Host files on HTTPS and link instead when possible. If attachments are required for operational mail, keep sizes modest and file types expected for your industry.

Image-only emails with little text often score poorly in SpamAssassin and accessibility review. Balance visuals with readable text; include alt attributes. Checklist should flag image-heavy templates before full send.

Track image hosting domain reputation separately from sending domain. Compromised CDNs or expired image domains break emails in inbox and erode trust. Verify image URLs during checklist review, not only at template design time.

Disaster recovery when checklist fails mid-campaign

Even disciplined teams hit surprises: a DNS record expires mid-send, a provider rotates credentials, or bounce rates spike after hour two. Define abort criteria before launch — for example, hard bounce rate above two percent or deferrals above ten percent — and assign who can pause MailFleet campaigns without waiting for executive approval.

When thresholds breach, stop new batches first, then export logs and classify failures using bounce code lookup. Fix root cause — authentication, list segment, or template — before resuming at reduced volume. Document the incident in the same repository where checklist evidence lives so auditors see both preparation and response.

Post-incident, update the checklist version if a gap appeared: missing monitoring step, unclear owner, or untested webhook. Deliverability preparation includes knowing how to recover, not only how to start.