Mail-tester vs Email on Acid by Sinch
Side-by-side from the Top 11 ranking of The 11 Best Email Deliverability Tools. Last verified June 15, 2026.
The short answer
Mail-tester ranks higher on Top 11 (#3 vs #6) for Email marketers and developers improving inbox placement rates. The fastest, simplest tool for a single pre-send spam check and technical audit.
At a glance
| Mail-tester | Email on Acid by Sinch | |
|---|---|---|
| Top 11 rank | #3 / The 11 Best Email Deliverability Tools | #6 / The 11 Best Email Deliverability Tools |
| Score (out of 9.4) | 8.8 | 8.1 |
| Best for | Quick, on-demand spam checks | Pre-send testing workflow |
| Pricing | $ (Pay-as-you-go or $50/mo) | $$ ($99 to $599/mo) |
| HQ | London, UK | Denver, USA |
| Founded | 2014 | 2009 |
Mail-tester
The fastest, simplest tool for a single pre-send spam check and technical audit.
www.mail-tester.com/Email on Acid by Sinch
Combines elite email rendering previews with capable deliverability and blocklist monitoring.
www.emailonacid.com/Methodology and scoring weights live at /methodology. No vendor pays for placement — see about.