InboxGreen vs Postmark

These tools solve different problems. Here is which one you need.

Short answer: Postmark is a transactional email sending service - you use it to send emails from your application or website. InboxGreen is an email authentication tool - you use it to check and fix SPF, DKIM, and DMARC so the emails you send (from any service) reach the inbox. If your emails sent via Postmark are going to spam, InboxGreen can diagnose the DNS authentication side of the problem.

Postmark

Transactional email sending

Send transactional emails (receipts, notifications, password resets) reliably from your app via SMTP or API. Built for high deliverability through dedicated sending infrastructure.

Free: 100 emails/month

Paid from $15/month (10,000 emails)

InboxGreen

Email authentication fix kit

Check SPF, DKIM, and DMARC for any domain. Get copy-paste DNS fix records for Cloudflare, Namecheap, GoDaddy, and more. Works regardless of how you send email.

Free check - no account needed

FixKit $29 one-time - Monitor from $19/mo

Feature comparison

Feature InboxGreen Postmark
Send transactional email No - InboxGreen does not send email Yes - via SMTP or REST API
Check SPF / DKIM / DMARC Yes - free DNS lookup, no account needed Partial - spam check add-on via API
Generate copy-paste DNS fix records Yes - formatted for your DNS provider No
DKIM setup for your domain Check + generate DKIM records free Sets up DKIM for your sending domain
SPF record generator Free - try it No
DMARC record generator Free - try it No
Email delivery tracking and opens No Yes - full analytics and webhooks
Bounce management No Yes - automatic bounce handling
Ongoing DNS monitoring + alerts Yes - from $19/mo No DNS monitoring
Blacklist check Free - try it No
No account required for basic check Yes Account required for all use

When to use Postmark

  • You are a developer who needs to send transactional email (receipts, password resets, notifications) from an application.
  • You want reliable email delivery infrastructure with dedicated IPs and high sender reputation.
  • You need delivery tracking, webhooks, and bounce management built in.
  • Your current email sending method (PHP mail, shared hosting SMTP) is unreliable.

When to use InboxGreen

  • Emails from your domain are going to spam and you need to check what is misconfigured.
  • You need to set up or fix SPF, DKIM, or DMARC records and want copy-paste DNS records for your provider.
  • You want ongoing monitoring that alerts you when DNS authentication records change or break.
  • You send email via Postmark, Gmail, Mailchimp, or any service, and want to verify your domain authentication is correct.

Pricing comparison

Postmark charges per email sent: $15/month for 10,000 emails, scaling up based on volume. It is a sending infrastructure cost, not a diagnostic tool cost.

InboxGreen pricing:

  • Free: Full SPF/DKIM/DMARC domain check, blacklist check, 15+ free tools - no account needed.
  • FixKit ($29 one-time): Copy-paste DNS records for your registrar + PDF guide. No subscription.
  • Monitoring ($19/month): Daily checks, email alerts when records change or fail, up to 5 domains.
  • Agency ($99/month): Up to 30 domains, white-label PDF reports.
Using Postmark but emails still hitting spam? Check your domain authentication first.
A free InboxGreen check will show whether your SPF, DKIM, and DMARC are configured correctly for your sending domain.
search Run Free Domain Check payments See Pricing

Frequently asked questions

Do I need InboxGreen if I already use Postmark?

Postmark sets up DKIM for its own sending infrastructure, but your domain's SPF and DMARC records still need to be configured correctly. If your SPF record does not include Postmark's sending servers, or your DMARC policy is misconfigured, emails may still fail authentication checks at receiving mail servers. InboxGreen checks all three (SPF, DKIM, DMARC) for your domain so you can catch and fix those issues.

Can InboxGreen replace Postmark?

No. InboxGreen does not send email. It checks and fixes the DNS configuration that affects whether email you send reaches the inbox. Postmark is the sending layer; InboxGreen is the authentication diagnostic layer. They solve different problems.

I am using Postmark and my emails are going to spam - what should I check?

Start with InboxGreen's free domain check to verify SPF, DKIM, and DMARC are configured correctly for your domain. Postmark provides DKIM for its sending infrastructure, but you still need SPF to include Postmark's servers and a DMARC policy to protect your domain. If authentication passes, the issue may be content, recipient engagement, or list quality rather than DNS configuration.

What is the best Postmark alternative for sending email?

Postmark competes with SendGrid, Mailgun, and AWS SES for transactional sending. InboxGreen is not a Postmark alternative - it solves a different problem (DNS authentication vs email delivery infrastructure).