Email Deliverability Is a Technical Problem

When your SaaS application sends a password reset email, invoice notification, or account activation link, it must reach the user's inbox — not spam folder, not bounced, not silently dropped. Email deliverability is a complex technical challenge involving DNS configuration, sender reputation, content filtering, and ongoing monitoring. At Nexis Limited, our SaaS products send thousands of transactional emails daily with high deliverability rates.

Email Authentication (SPF, DKIM, DMARC)

SPF (Sender Policy Framework)

SPF is a DNS record that specifies which mail servers are authorized to send email on behalf of your domain. When a receiving server gets an email from your domain, it checks the SPF record to verify the sending server is authorized. Without SPF, your emails are more likely to be flagged as spam.

DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to each email. The sending server signs the email with a private key, and the receiving server verifies the signature using a public key published in DNS. This proves the email was not tampered with in transit and was actually sent by your domain.

DMARC (Domain-based Message Authentication, Reporting and Conformance)

DMARC builds on SPF and DKIM, telling receiving servers what to do when authentication fails (none, quarantine, reject) and providing reporting on authentication results. Start with DMARC policy "none" to monitor, then move to "quarantine" and eventually "reject" as you verify legitimate email sources.

Using an Email Service Provider

For SaaS applications, use a dedicated email service provider (SendGrid, Postmark, Amazon SES, Mailgun) rather than sending email from your own servers. Benefits:

  • Pre-established sender reputation and IP warming.
  • Deliverability monitoring and analytics.
  • Automatic bounce and complaint handling.
  • SPF and DKIM configuration support.
  • Dedicated IP addresses for high-volume senders.

Transactional vs Marketing Emails

Separate transactional emails (password resets, invoices, account notifications) from marketing emails (newsletters, promotions). Use different sending domains or IP addresses so that marketing email complaints do not affect transactional email deliverability. Transactional emails should never be blocked because marketing emails harmed your sender reputation.

Content Best Practices

  • Use a recognizable "From" name and email address.
  • Keep subject lines clear and relevant — avoid spam trigger words.
  • Include a plain text version alongside HTML.
  • Maintain a reasonable text-to-image ratio.
  • Include an unsubscribe link for any email that is not strictly transactional.
  • Personalize emails with the recipient's name and relevant context.

Monitoring Deliverability

  • Track delivery rates, open rates, bounce rates, and spam complaint rates.
  • Monitor blacklists — check if your sending IPs or domains appear on any major blacklists.
  • Set up feedback loops with major inbox providers (Gmail, Outlook, Yahoo) to receive spam complaints.
  • Alert on delivery rate drops — they indicate deliverability problems that need immediate investigation.

Handling Bounces and Complaints

  • Remove hard bounces (invalid addresses) immediately — continuing to send to invalid addresses damages sender reputation.
  • Handle soft bounces (temporary failures) with retry logic — but stop after several failures.
  • Honor unsubscribe requests immediately — delays violate CAN-SPAM and GDPR.
  • Process spam complaints by removing the complainant from future sends.

Conclusion

Email deliverability is a technical discipline that requires proper DNS configuration, sender reputation management, and ongoing monitoring. Most SaaS applications should use a dedicated email service provider and implement SPF, DKIM, and DMARC from day one. The cost of poor deliverability — users who cannot access their accounts or receive important notifications — far exceeds the investment in proper email infrastructure.

Having email deliverability issues? Our team can audit and optimize your email infrastructure.