Email Deliverability Best Practices

Email deliverability is shared between your sending domain, audience quality, message content, and mail provider. Migma helps with domain setup, validation, suppression, rendering checks, and preflight review, but inbox placement is never guaranteed. Use this page as an operating checklist before important sends.

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Delivery Readiness

Check these four areas before any high-volume or important campaign.

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Start With Consent

Mailbox providers look at recipient behavior. People who expected your email are more likely to open, click, reply, or ignore it without complaint. People who did not expect it are more likely to bounce, unsubscribe, or mark it as spam. Before importing or sending to a list, confirm:

• Contacts opted in through a form, checkout flow, account setting, event registration, or another clear consent path.
• The email type matches the consent they gave, such as newsletter, lifecycle, product update, or transactional.
• Suppressed, bounced, complained, and unsubscribed contacts remain excluded.
• Segment criteria match the message. Do not send broad campaigns to people with weak or stale intent.

Related: GDPR newsletter consent, CAN-SPAM checklist, CSV Upload.

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Authenticate Your Sending Domain

Authentication proves that your email provider is allowed to send mail for your domain. Major inbox providers expect authenticated mail, and bulk senders should treat SPF, DKIM, and DMARC as required. In Migma: Use Add a Sending Domain for the full setup flow. If a record does not verify, see Verification Issues.

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Keep Complaint Rate Low

User-reported spam is one of the clearest negative signals. Google’s sender guidelines recommend keeping user-reported spam below 0.1% and preventing it from reaching 0.3% or higher. Migma’s own domain health thresholds are stricter for managed domains because shared infrastructure needs tighter controls. To reduce complaints:

• Send only to contacts with clear consent.
• Set expectations at signup about content and frequency.
• Use a recognizable sender name and a monitored reply address.
• Make the subject line match the email body.
• Avoid sending too often to inactive contacts.
• Make unsubscribe easy before people reach for the spam button.

Track domain status in Domain Health and campaign results in Track Results.

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Make Unsubscribe Easy

Marketing and promotional email should include a visible unsubscribe or preference link in the message body. Large senders also need one-click unsubscribe headers for Gmail and Yahoo inbox requirements. Good unsubscribe behavior:

• Keep the unsubscribe or preference link visible in the footer.
• Do not require login to opt out.
• Honor opt-outs quickly. Migma suppression flows are designed to apply immediately to marketing sends.
• Offer topic or frequency choices when that helps subscribers stay on the right list.
• Never send marketing campaigns to suppressed contacts.

Related: Preference Center, Suppression List, CAN-SPAM Checklist.

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Warm New Domains Gradually

New domains have little or no reputation. Sending a large campaign immediately can look suspicious, even when the audience opted in. Use warming when:

• The domain or subdomain is new.
• You are moving from one email service provider to another.
• You have not sent consistent volume recently.
• You plan to increase volume significantly.

During warming:

• Start with engaged subscribers first.
• Send consistently within the daily limit.
• Pause broad campaigns if bounces or complaints rise.
• Avoid sudden jumps in volume or frequency.

See Domain Warming for Migma’s configurable warming plan and safety thresholds.

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Keep the List Clean

List quality has more impact than small copy tricks. Bounces, disposable addresses, role inboxes, spam traps, and long-inactive contacts all weaken reputation. Use Migma to:

• Validate new contacts during import.
• Re-validate stale subscribed contacts.
• Exclude risky addresses from sends.
• Review skipped recipients after each campaign.
• Keep bounces, complaints, unsubscribes, and manual blocks suppressed.

For high-stakes campaigns, build a segment from recently engaged, valid contacts first. Then expand carefully after you confirm healthy delivery, bounce, complaint, open, and click signals. Related: Deliverability & Validation, Skipped Recipients, Suppression List.

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Send Relevant, Readable Email

Content still matters, but modern filtering is not about one magic word. Inboxes evaluate whether the message looks legitimate, matches recipient expectations, renders correctly, and gets healthy engagement. Before sending, review:

• Subject line: truthful, specific, and aligned with the email body.
• Sender identity: recognizable brand or person, not a misleading alias.
• Layout: readable on mobile, clear hierarchy, no image-only email.
• Links: relevant destinations, no broken URLs, no unnecessary redirect chains.
• Images: compressed, useful alt text, and enough live text if images are blocked.
• Accessibility: readable contrast, descriptive link text, and scannable structure.
• Dark mode: text, logos, buttons, and backgrounds stay legible.

For rendering details, see Email Client Compatibility.

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Run Preflight Before Important Sends

Preflight checks the email Migma will actually send or export. Use it before production campaigns, especially after editing copy, links, images, or layout. Preflight does not replace good list quality or domain reputation. It helps catch issues in the email itself before subscribers see them.

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Monitor After Sending

Deliverability work continues after send. Watch each campaign and domain over time so small issues do not become reputation problems. If performance drops, narrow the next send to recent engagers, clean or re-validate the audience, review signup expectations, and check domain health before increasing volume again.

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Pre-Send Checklist

Before an important campaign:

• Audience has clear permission for this email.
• Suppressed, bounced, complained, and unsubscribed contacts are excluded.
• Sending domain is verified with SPF, DKIM, DMARC, and MAIL FROM.
• New domain is warming or already has steady sending history.
• Subject line matches the message.
• From name and reply-to are recognizable and monitored.
• Unsubscribe or preference link is visible and working.
• Email has enough live text if images are blocked.
• Mobile and dark mode previews are readable.
• Links work and use relevant destinations.
• Email Preflight has been run after final edits.
• Test email has been reviewed in a real inbox.

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