Folderly 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
Folderly ranks higher on Top 11 (#5 vs #6) for Email marketers and developers improving inbox placement rates. A specialized platform for fixing deliverability problems common in cold email campaigns.
At a glance
| Folderly | Email on Acid by Sinch | |
|---|---|---|
| Top 11 rank | #5 / The 11 Best Email Deliverability Tools | #6 / The 11 Best Email Deliverability Tools |
| Score (out of 9.4) | 8.3 | 8.1 |
| Best for | Fixing cold outreach deliverability | Pre-send testing workflow |
| Pricing | $$$ ($200 to $2000/mo) | $$ ($99 to $599/mo) |
| HQ | Wilmington, USA | Denver, USA |
| Founded | 2019 | 2009 |
Folderly
A specialized platform for fixing deliverability problems common in cold email campaigns.
folderly.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.