Email deliverability and form submissions

Why forms fail silently

Form submissions can fail without users knowing. The form appears to work. Users see a success message. But the email never arrives.

This costs enquiries, sales, and trust. Users assume you received their message. You assume they did not contact you. Both sides lose.

Common failure points

Client-side only validation

Relying only on JavaScript validation is risky. JavaScript can be disabled, blocked, or fail to load.

• Always validate on the server, even if you also validate on the client [1]Source 1 .
• Server-side validation ensures forms work even when JavaScript fails.
• Client-side validation improves user experience but cannot be trusted alone.

Email delivery failures

Email delivery can fail for many reasons.

• Server configuration problems.
• Emails marked as spam by filters.
• Missing or incorrect SPF, DKIM, and DMARC records.
• Reputation issues with the sending domain or IP.
• Rate limiting or blocking by email providers.

Missing error handling

If email sending fails, users need to know. Otherwise they assume the form worked.

• Catch email sending errors and show clear messages to users.
• Log errors for debugging.
• Provide alternative contact methods when email fails.

Email deliverability basics

What deliverability means

Deliverability is whether emails reach inboxes instead of spam folders. It depends on technical setup, reputation, and content.

SPF, DKIM, and DMARC

These DNS records help email providers trust your emails.

• SPF lists which servers can send email for your domain.
• DKIM cryptographically signs emails to prove they came from your domain.
• DMARC tells providers what to do with emails that fail SPF or DKIM checks.

Without these records, emails are more likely to be marked as spam. Many email delivery services handle this configuration for you.

Reputation matters

Email providers track sender reputation. Poor reputation means emails go to spam, even with correct technical setup.

• Sending from a shared server with poor reputation hurts your emails.
• High bounce rates and spam complaints damage reputation.
• Using a reputable email delivery service protects your reputation.

Why use an email delivery service

Sending emails directly from your server is possible but risky. Email delivery services handle the complexity for you.

Reliability

• Professional services maintain high deliverability rates.
• They handle SPF, DKIM, and DMARC configuration.
• They monitor reputation and handle issues proactively.

Infrastructure

• They run infrastructure designed for email delivery.
• They handle scaling, rate limiting, and retries.
• They provide APIs that are easier to integrate than SMTP.

Monitoring and insights

• They provide delivery status, bounce tracking, and analytics.
• You can see which emails were delivered, bounced, or marked as spam.
• This helps diagnose problems quickly.

Resend API example

Services such as Resend API provide reliable email delivery with simple integration. They handle deliverability, reputation management, and provide clear delivery status. This removes the complexity of managing email infrastructure yourself.

Using a service like Resend means:

• Emails are more likely to reach inboxes.
• You get delivery status and error reporting.
• SPF, DKIM, and DMARC are configured correctly.
• You can focus on your site instead of email infrastructure.

Building reliable forms

Server-side processing

Always process forms on the server. Never rely only on client-side JavaScript.

• Validate all input on the server [1]Source 1 .
• Sanitise data before using it.
• Handle errors gracefully and inform users.

Clear error messages

When forms fail, tell users what went wrong [3]Source 3 .

• Show specific errors for each field that has a problem [4]Source 4 .
• Explain what users need to fix.
• Keep error messages clear and helpful [2]Source 2 .

Success confirmation

When forms succeed, confirm it clearly.

• Show a clear success message.
• Send a confirmation email to the user if appropriate.
• Make it obvious what happens next.

Spam protection

Protect forms from spam without hurting real users.

• Use honeypot fields that are invisible to users but catch bots.
• Validate content quality, not just presence.
• Avoid CAPTCHAs that block users with disabilities [1]Source 1 .

Testing form submissions

Test regularly

Test your forms regularly to catch problems early.

• Submit test forms monthly.
• Check that emails arrive in the right inbox.
• Verify email formatting and content.
• Test with JavaScript disabled to ensure server-side processing works.

Monitor for failures

• Set up error logging for form submission failures.
• Monitor email delivery status if your service provides it.
• Watch for bounce rates or delivery problems.
• Check spam folder placement if possible.

Test error handling

• Test what happens when email sending fails.
• Verify error messages are clear and helpful.
• Ensure users can retry or use alternative contact methods.

What to look for in an email service

• High deliverability rates and good reputation.
• Clear API documentation and easy integration.
• Delivery status and error reporting.
• Automatic handling of SPF, DKIM, and DMARC.
• Reasonable pricing for your volume.
• Good support and documentation.

Red flags to avoid

• Sending emails directly from shared hosting without proper configuration.
• Using free email services for business form submissions.
• Ignoring bounce rates and delivery problems.
• Not testing forms regularly.
• Relying only on client-side validation.
• Not providing alternative contact methods when email fails.

Alternative contact methods

Even with reliable email delivery, provide alternatives.

• Include a phone number for urgent enquiries.
• Provide a postal address where appropriate.
• Offer live chat if it fits your workflow.
• Make it clear how users can follow up if they do not hear back.

Next step

Test your forms today. Submit a test form and verify the email arrives. Check your spam folder. Review your email delivery setup. If you are sending directly from your server, consider using a professional email delivery service. Services like Resend API handle deliverability complexity and provide reliable delivery with clear status reporting. Then test regularly and monitor for problems. Reliable form submission protects your enquiries and your reputation. If you need help with form implementation or email delivery, get in touch to discuss your needs. For help with form accessibility, see what an accessibility audit includes.