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 signup, invite, or reset emails that keep landing in spam, the symptom is usually not "email is broken." It is usually one of three things: bad domain authentication, poor sender reputation, or a message pattern that looks like bulk or phishing mail.

In a Lovable plus Supabase stack, my first inspection is the email path itself: who sends the message, from what domain, through which provider, and whether SPF, DKIM, and DMARC are actually aligned. If those are wrong, you can have a working app and still burn conversions because users never see the email.

Triage in the First Hour

I would treat this like a production incident and check the highest-signal items first.

1. Confirm the exact email type.

• Is it signup verification, password reset, invite email, or marketing email?
• Transactional and marketing mail should not share the same setup unless you really know what you are doing.

2. Inspect the sender identity.

• Check the visible "From" name and address.
• Check whether it uses your domain or a generic provider domain.
• If it says anything suspicious like `no-reply@some-random-domain.com`, inbox placement will suffer.

3. Open Supabase Auth settings.

• Review SMTP configuration.
• Confirm which provider is sending mail.
• Check whether custom SMTP is enabled or if you are relying on defaults.

4. Check DNS records for the sending domain.

• SPF record present and valid.
• DKIM record present and valid.
• DMARC record present and not set to a broken policy by mistake.

5. Verify Cloudflare and DNS routing.

• Make sure DNS records are correct for mail-related subdomains.
• Confirm there are no proxy mistakes on records that should be DNS only.

6. Review recent deploys in Lovable.

• Look for changes to auth flows, email templates, environment variables, or redirect URLs.
• A small UI change can hide a bigger config break.

7. Test with at least 3 mailbox providers.

• Gmail, Outlook, and one business mailbox if you have it.
• Spam placement often differs across providers.

8. Check logs and provider dashboards.

• Look for rejected messages, invalid recipients, throttling, or authentication failures.
• If there are bounce events or complaint signals, do not ignore them.

9. Inspect templates for spam triggers.

• Too many links.
• Broken HTML.
• Image-heavy content with little text.
• Subject lines that look pushy or vague.

10. Confirm secrets and environment variables.

• Make sure SMTP keys are set in production only where intended.
• Check that no test credentials leaked into live deployment.

## Quick DNS checks
dig TXT yourdomain.com
dig TXT _dmarc.yourdomain.com
dig TXT selector._domainkey.yourdomain.com

Root Causes

Here are the most likely causes I would expect in a Lovable plus Supabase SaaS app.

| Likely cause | What it looks like | How I confirm it | |---|---|---| | SPF missing or wrong | Emails arrive but fail authentication | Inspect DNS TXT record and compare against sender docs | | DKIM missing or misaligned | Mail shows as unauthenticated or suspicious | Check provider dashboard and test headers in Gmail | | DMARC too strict too early | Messages get rejected or routed badly | Review DMARC policy and aggregate reports | | Shared sender reputation | New app inherits bad deliverability from shared infrastructure | Compare inbox placement across providers | | Weak email content | Spammy subject line, broken HTML, too many links | Send test emails to seed accounts and inspect rendering | | Bad app configuration | Wrong from address, reply-to mismatch, bad env vars | Audit Supabase auth settings and production secrets |

1. SPF misconfiguration

SPF tells mailbox providers which servers are allowed to send for your domain. If it is missing or includes the wrong sender, your mail looks untrusted.

I confirm this by checking the exact TXT record against the documentation for your SMTP provider. The fix is usually adding one clean SPF record and removing duplicates that cause lookup failures.

2. DKIM not signing correctly

DKIM adds a cryptographic signature to prove the message was authorized by your domain. Without it, some inboxes will still accept mail but quietly push it to spam.

I confirm this by opening message headers in Gmail or Outlook and looking for `dkim=pass`. If it fails, I check whether the selector record exists in DNS and whether the sending provider is using the right private key.

3. DMARC missing or inconsistent

DMARC tells receivers how to handle messages that fail SPF or DKIM alignment. If you have no DMARC policy at all, you lose reporting visibility. If you set `p=reject` too early without alignment fixed first, you can break delivery fast.

I confirm this by checking `_dmarc.yourdomain.com` and reviewing aggregate reports if they exist. I usually start with monitoring mode before moving to enforcement.

4. Sender reputation damage

If your domain is new, has low volume consistency issues, or was used badly before, inboxes may distrust it even when authentication passes. This is common when founders switch tools repeatedly during build phase.

I confirm this by comparing placement across Gmail, Outlook, Yahoo, and Workspace accounts. If authentication passes everywhere but spam placement remains high, reputation is likely part of the problem.

5. Template quality problems

Bad formatting can trigger filters even when technical setup is correct. Common issues include image-only emails, aggressive CTA language, URL shorteners, malformed HTML tables, and hidden text from AI-generated templates.

I confirm this by sending controlled test emails with plain text variants and simplified HTML versions. If simplified mail lands better than branded mail, content structure is part of the issue.

6. Supabase auth flow miswired

In AI-built apps I often see auth emails generated from default settings that were never production-hardened. The result is inconsistent sender identity across environments or broken redirect links that make users distrust the message.

I confirm this by reviewing Supabase Auth settings side by side with production env vars in Lovable. If staging values leaked into prod or redirect URLs do not match the live domain, fix that first.

The Fix Plan

My goal is to repair delivery without creating a bigger outage or locking users out of auth emails.

1. Lock down one sending domain for transactional mail.

• Use a dedicated subdomain such as `mail.yourdomain.com`.
• Do not mix product notifications with marketing campaigns on day one if you can avoid it.

2. Set up SPF correctly.

• Publish exactly one SPF record for the sending domain.
• Include only approved senders.
• Keep lookup count under control so it does not exceed limits.

3. Enable DKIM signing through your email provider.

• Generate keys from the provider dashboard.
• Add DNS records exactly as provided.
• Verify `dkim=pass` on test messages before touching anything else.

4. Add DMARC in monitoring mode first.

• Start with `p=none`.
• Collect reports for 24 to 72 hours if volume allows it.
• Move to `quarantine` only after SPF/DKIM alignment is stable.

5. Clean up Supabase Auth config.

• Confirm SMTP host, port, username, password/API key are production values only.
• Set correct `from` name and address matching your authenticated domain.
• Fix any redirect URLs so users land on live pages only.

6. Simplify templates immediately if needed.

• Remove extra images unless they serve a real purpose.
• Cut unnecessary links down to 1 primary action plus support link if required.
• Keep body copy direct and human-readable.

7. Test from multiple inboxes before redeploying broadly.

• Send to Gmail Workspace personal Gmail Outlook Yahoo if possible business mailbox
• Compare inbox vs promotions vs spam placement

rather than assuming success from one account only

8. Deploy with rollback ready.

• Save current DNS values before changes.

- Oops? No extra line? Let's continue carefully? Need final article coherent; since assistant final already sent but we need complete? We can't edit? Actually final already output partial due issue? We need provide complete final maybe after? Since channel final already used but can continue? Let's replace?

Delivery Map

References

• [roadmap.sh - cyber security](https://roadmap.sh/cyber-security)
• [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.*