Skip to content
All articles
Product22 May 2025·3 min read

Email deliverability troubleshooting guide

Every feature carries a maintenance bill that comes due long after the launch post.

Paycux engineering

Every feature carries a maintenance bill that comes due long after the launch post. The useful discipline is deciding, up front, who is going to pay it.

This piece walks through how we think about it at Paycux, what we have changed our minds about, and where the sharp edges are.

How email delivery works (and fails)

Consider how email delivery works (and fails). Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Ship the smallest version that is honest about its limits. A feature that does one thing completely beats one that does five things with an asterisk on each.

How Paycux sends emails

How Paycux sends emails is where this gets concrete. Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

  • Choose defaults as carefully as features
  • Settle the name before you ship the thing
  • Ship the smallest honest version
  • Say plainly what the feature does not do

Troubleshooting checklist

Troubleshooting checklist deserves its own treatment. Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Determine the scope of the problem

Determine the scope of the problem is where this gets concrete. Ship the smallest version that is honest about its limits. A feature that does one thing completely beats one that does five things with an asterisk on each.

Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Defaults are the product.

Check your email sending service logs

Check your email sending service logs deserves its own treatment. Ship the smallest version that is honest about its limits. A feature that does one thing completely beats one that does five things with an asterisk on each.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Verify DNS records (SPF, DKIM, DMARC)

Consider verify dns records (spf, dkim, dmarc). Ship the smallest version that is honest about its limits. A feature that does one thing completely beats one that does five things with an asterisk on each.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Assess sender reputation and blacklists

Consider assess sender reputation and blacklists. Defaults are the product. Most people will never open the settings screen, which means the behaviour you chose for them is the behaviour they will experience forever.

Naming is design work. If the team argues about what to call something, the disagreement is usually about what it is, and shipping before that is settled means shipping the confusion to customers.

Where this leaves us

The pattern repeats across every system we have looked at: the hard part is not the mechanism, it is keeping the mechanism honest as the surrounding assumptions change.

If you are working through the same problem and want to compare notes, the docs cover the mechanics and the console shows the behaviour on your own data.

Everything here, already built

Sign-in, enterprise SSO, directory provisioning, roles and an audit trail behind one API. Start with the quickstart and have a working sign-in this afternoon.

Start selling to enterprise customers

Create an account, point sign-in at Paycux, and get back to the part of the product that is actually yours.