Cllavio.
LoginGet Started
OverviewFeaturesPricingContact

How to Keep Your Emails Out of Spam

A practical, no-fluff guide: subjects, body copy, links, sending habits, and the technical setup that inboxes expect.

Overview

Inbox placement is a mix of content quality, list health, and domain reputation. Follow the sections below and you’ll avoid the most common spam triggers while building long-term deliverability.

Quick Checklist

Do ✅

  • Authenticate your domain (SPF, DKIM, DMARC).
  • Send to engaged, opted-in recipients only.
  • Use clear subjects & human-sounding copy.
  • Keep HTML clean; provide a plain-text part.
  • Link to reputable, branded domains.
  • Include a visible unsubscribe link.

Avoid ❌

  • Purchased lists or scraped contacts.
  • ALL CAPS!!!, excessive emojis 😱😱, or $$$ claims.
  • Too many images or one big image-as-email.
  • URL shorteners or raw IP links.
  • Attachments with risky file types.
  • Sudden volume spikes (warm up first).

Subject Lines

Subjects should be specific, honest, and conversational. Avoid clickbait, shouting (ALL CAPS), and spammy promises.

Good examples

Order #8421 — shipped today
Welcome to Acme — getting started in 3 steps
Your April usage report is ready
A quick check-in about your trial

Risky examples

MAKE MONEY FAST $$$
READ THIS NOW!!!!!
You won't believe this trick...
WIN a FREE iPhone today

Tip: Keep it ~40–60 characters where possible. Use preheader text to add context.

Body Content

Sound like a person, not a billboard. Lead with value, keep layouts simple, and always include a plain-text alternative.

Recommended structure

Hi {{first_name}},

Thanks for joining Acme! Here are your next steps:

1) Set your password: https://acme.com/account/setup
2) Add your team: https://acme.com/team/invite
3) Explore templates: https://acme.com/templates

If you have questions, just reply to this email — we're here to help.

—
Maya from Acme
123 Market St, City
Unsubscribe: https://acme.com/unsubscribe/{{token}}

Do

  • Use short paragraphs and clear calls to action.
  • Balance text and images; keep HTML tidy.
  • Include a physical address and unsubscribe link.
  • Offer a real reply path (monitored inbox).

Avoid

  • Single giant image as the entire email.
  • Hidden text, invisible links, or mismatched fonts.
  • Too many CTAs that read like ads.
  • Misleading content or false urgency.

From & Reply-To

  • Use a consistent, recognizable From name and address.
  • A monitored Reply-To increases trust and engagement.
  • Avoid frequent From/Reply-To changes; it confuses filters and users.

Sending Practice

  • Warm up new domains/IPs: start small, grow gradually.
  • Match cadence to engagement; reduce volume to inactive users.
  • Segment by behavior (active vs. dormant) to protect reputation.
  • Avoid big spikes; schedule sends to smooth delivery.

List Hygiene

  • Collect explicit opt-ins; confirm when possible.
  • Regularly suppress bounces, complaints, and long-term inactives.
  • Use clear forms and expectations to reduce spam complaints.

SPF, DKIM & DMARC

Modern inboxes expect authenticated mail. Set DNS records for the domain you send from. Align your visible From domain with the domain you authenticate.

SPF

Authorizes which servers can send mail for your domain.

DKIM

Cryptographically signs messages so receivers can verify they weren’t altered.

DMARC

Tells receivers how to handle mail that fails SPF/DKIM; enables reporting.

Attachments

  • Keep total size small; link to downloads when possible.
  • Avoid executable formats; prefer PDF/PNG/JPG.
  • Only include attachments the recipient expects.

Test Before You Send

  • Send to a seed list across major providers (Gmail, Outlook, Yahoo, iCloud).
  • Check the spam score of content; remove trigger phrases.
  • Verify that links, tracking, and unsubscribe work correctly.
  • Preview both HTML and plain-text parts; test on mobile.

Troubleshooting

High bounces

  • Stop sending to bad domains/typos immediately.
  • Use double opt-in and real-time validation on forms.

Low opens

  • Refresh segments to engaged users only.
  • Test new subjects & send times; reduce frequency to inactives.

Spam placement

  • Confirm SPF/DKIM pass and DMARC alignment.
  • Remove spammy copy; avoid link shorteners.
  • Warm volume gradually; prune unengaged contacts.

Image-heavy templates

  • Increase text-to-image ratio; add alt text.
  • Provide a legible plain-text part.
Back to top