How I Would Fix emails landing in spam in a Lovable plus Supabase AI-built SaaS app Using Launch Ready.

How I Would Fix emails landing in spam in a Lovable plus Supabase AI-built SaaS app Using Launch Ready

If your SaaS is sending emails but they keep landing in spam, the most likely problem is not "email content". It is usually domain reputation, missing authentication, or a bad sending setup tied to the wrong domain. In a Lovable plus Supabase app, I would first inspect the sender domain, the SMTP provider, and whether SPF, DKIM, and DMARC are actually aligned with the From address users see.

The first thing I would check is simple: what exact domain is sending the email, and does that domain have clean DNS records in Cloudflare or wherever DNS is managed. If that foundation is wrong, you can rewrite copy all day and still lose inbox placement.

Triage in the First Hour

1. Check the actual From address in the app.

• Confirm whether emails are sent from a custom domain or a generic provider domain.
• Look for mismatches between `no-reply@yourapp.com` and the SMTP account domain.

2. Inspect Supabase email settings.

• Review auth templates, SMTP config, and any webhook or edge function that sends mail.
• Confirm whether password reset, invite, and onboarding emails use the same sender path.

3. Open DNS in Cloudflare or your registrar.

• Verify SPF, DKIM, and DMARC records exist for the sending domain.
• Check for duplicate SPF records or broken TXT formatting.

4. Review email provider logs.

• Look at delivery status, bounce rate, complaint rate, deferrals, and authentication results.
• If you see high soft bounces or spam complaints, stop sending until fixed.

5. Test inbox placement manually.

• Send to Gmail, Outlook, and one business mailbox.
• Check whether mail lands in inbox, promotions, updates, or spam.

6. Inspect app build and environment variables.

• Confirm production secrets are set correctly.
• Make sure no test SMTP credentials are being used in production.

7. Review recent deploys.

• If email behavior changed after a release, compare old and new env vars, templates, sender names, and link domains.

8. Check link domains inside the email.

• If links point to a different or untrusted domain than the sender domain, spam filtering gets worse.
• Make sure redirects are clean and SSL is valid.

9. Audit any AI-generated email copy.

• Look for spammy phrases, too many links, image-only content, or vague subject lines.
• AI-written copy often looks fine to humans but triggers filters because it is repetitive or sales-heavy.

10. Confirm API security basics around mail sending.

• Ensure only authenticated server-side code can trigger transactional email sends.
• Prevent abuse that could destroy sender reputation through mass sends.

## Quick DNS sanity checks
dig TXT yourdomain.com
dig TXT _dmarc.yourdomain.com
dig TXT selector1._domainkey.yourdomain.com

Root Causes

| Likely cause | How to confirm | Why it sends mail to spam | |---|---|---| | Missing SPF | Check DNS TXT records for exactly one SPF entry | Mail receivers cannot verify authorized senders | | Broken DKIM | Compare provider DKIM setup with DNS record values | Messages fail cryptographic signing checks | | No DMARC policy | Look for `_dmarc` TXT record | Receivers have no alignment policy to trust | | Wrong From domain | Compare SMTP envelope sender vs visible From address | Alignment fails even if mail technically sends | | Shared or poor sender reputation | Check provider dashboard for complaint/bounce history | Other senders on same pool can hurt deliverability | | Spammy content or bad links | Review subject lines, body copy, images, and redirect chains | Filters score aggressive language and suspicious URLs higher |

1. Missing SPF

I would confirm this by checking that there is one valid SPF record for the sending domain. If there are two SPF TXT records, many receivers treat that as a failure.

The fix is usually to merge them into one record and include only the services you actually use. Do not add random vendors "just in case".

2. DKIM not signing correctly

I would verify that your mail provider gave you a selector and public key pair that matches DNS exactly. If DKIM is missing or misconfigured, Gmail and Outlook will distrust your mail even if it arrives.

A common mistake in AI-built apps is copying old settings from staging into production. That creates a false sense of safety because the app works while deliverability quietly collapses.

3. DMARC missing or too weak

I would check whether `_dmarc.yourdomain.com` exists at all. If it does not exist, you have no policy telling receivers how to handle failed authentication.

Start with `p=none` to collect reports safely if this is brand new. Then move toward `quarantine` or `reject` once alignment is stable.

4. Sender identity mismatch

I would compare:

• SMTP account domain
• Visible From address
• Return-path / envelope-from
• Link domains used inside emails

If these do not line up cleanly under one trusted brand domain, spam placement gets worse fast. This is especially common when founders send from a free mailbox but try to present as a product company.

5. Reputation damage from bad traffic

I would inspect whether your app has been abused to send too many emails too quickly. In an AI-built SaaS app this can happen through signup loops, invite abuse, bot registrations, or repeated password reset attempts.

This is also an API security issue. If an unauthenticated endpoint can trigger unlimited messages, attackers do not need to hack anything; they just burn your reputation for you.

6. Content patterns that trip filters

I would review subject lines like:

• "Act now"
• "Free offer"
• "Urgent verification"
• Excessive punctuation
• All caps
• Too many links
• Image-only layouts

These patterns are easy to generate with AI tools but often perform badly with inbox providers. The fix is usually boring: shorter copy, one clear CTA, fewer links.

The Fix Plan

My approach would be safe and staged so I do not make deliverability worse while fixing it.

1. Freeze unnecessary sends for 24 hours if reputation looks damaged.

• Pause marketing-style blasts first.
• Keep only critical transactional mail running if needed.

2. Move all sending onto one verified custom domain.

• Use a real business domain connected through Cloudflare DNS.
• Avoid free mailbox addresses for production SaaS mail.

3. Set up SPF correctly.

• Add one SPF record only.
• Include only approved providers such as your SMTP service and Supabase-related mail flow if applicable.

4. Enable DKIM signing in the email provider.

• Generate keys from the provider dashboard.
• Publish the exact DNS records they give you.

5. Add DMARC with reporting enabled.

• Start with monitoring mode so you can see failures without blocking legitimate mail immediately.
• Use aggregate reports to spot alignment issues quickly.

6. Standardize sender names and templates.

• Use one brand name across onboarding, invites, resets, receipts, and alerts.
• Remove aggressive sales language from transactional templates.

7. Fix link hygiene inside every template.

• Use your primary branded domain for links where possible.
• Remove unnecessary redirects and broken tracking parameters unless they are required.

8. Tighten API access around email triggers.

• Only server-side routes should send email.
• Add rate limits on signup and resend actions.
• Validate input so bots cannot flood your system with requests.

9. Warm up if volume has been low or erratic.

• Start with small volumes to engaged users first.
• Do not jump from 20 emails per day to 20k overnight unless your reputation history supports it.

10. Monitor after deployment for 48 hours.

• Watch bounce rate,

complaint rate, inbox placement samples, and auth pass rates daily until stable.

The goal is not just "send again". The goal is get back to consistent inbox delivery without breaking auth flows or creating support tickets about missing password resets.

Regression Tests Before Redeploy

Before I ship this fix back into production I want clear acceptance criteria:

• SPF passes on test messages sent to Gmail and Outlook accounts.
• DKIM passes on every transactional template tested.
• DMARC alignment matches the visible From domain on at least 95 percent of test sends.
• Password reset emails arrive within 60 seconds in normal conditions.
• Invite emails render correctly on mobile at 375 px width without clipped CTAs.
• No broken links appear in any template after clicking through all buttons manually.
• Rate limiting blocks repeated resend attempts after a defined threshold such as 5 requests per minute per user/IP pair where appropriate.
• Bounce handling logs failures without exposing secrets in application logs.
• Uptime monitoring confirms the mail-sending route stays healthy after redeploy.

I would also run an exploratory pass:

• Send from new user flows
• Send from admin flows
• Send from edge cases like long names or unusual company domains
• Test empty state behavior when SMTP fails
• Confirm fallback messaging tells users what happened without leaking internal details

For QA coverage I want at least:

• 100 percent of critical auth-related email flows tested manually before launch
• A smoke test suite covering signup,

reset, invite, and notification paths

• One test mailbox each on Gmail,

Outlook, and Apple Mail if possible

Prevention

If I were hardening this long term inside an AI-built SaaS app using Lovable plus Supabase plus Launch Ready standards, I would put guardrails around four areas:

1. Monitoring

• Track bounce rate,

complaint rate, open rate, send latency, auth pass rate, and DMARC failures daily during launch week.

• Alert me if bounce rate goes above 2 percent or complaint rate crosses 0.1 percent.

2. Code review

• Review any change touching email triggers,

environment variables, templates, redirect URLs, or auth flows before deploy.

• Small safe changes beat broad refactors here because deliverability regressions are expensive to diagnose later.

3. Security controls

• Treat outbound email as an API surface that needs auth checks,

input validation, rate limits, logging hygiene, and least privilege access to secrets.

• Never expose SMTP credentials client-side or in public repo history.

4. UX safeguards

• Show clear states when an email was sent,

when it may take time, and what users should do next if nothing arrives after 2 minutes? . Wait maybe typo? Need ASCII punctuation only; remove weird spacing? Let's continue carefully? Need final article coherent.]

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Let's continue:

Delivery Map

References

• [roadmap.sh - API security](https://roadmap.sh/api-security-best-practices)
• [OWASP API Security Top 10](https://owasp.org/www-project-api-security/)
• [MDN Web Docs - HTTP](https://developer.mozilla.org/en-US/docs/Web/HTTP)
• [Cloudflare DNS documentation](https://developers.cloudflare.com/dns/)
• [Sentry documentation](https://docs.sentry.io/)

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Take the next step

If this is a problem in your product right now, here is what to do next:

• [Use the free Cyprian tools](/tools) - estimate cost, score app risk, check launch readiness, or pick the right service sprint.

• [Book a discovery call](/contact) - I will tell you honestly whether you need a sprint or if you can DIY the next step.

*Written by Cyprian Tinashe Aarons - senior full-stack and AI engineer helping founders rescue, launch, automate, and scale AI-built products.*