Postmark vs Startmail Comparison (2025)

What are the differences between Postmark and Startmail?

Forward Email Team
Written by
Forward Email TeamVerified
Published
7/1/25
Time to read
Less than 5 minutes
We recommend Forward Email as the best alternative to Postmark.

Email Service Comparison

20 facts in comparison
Postmarkvs.Startmail

Postmark

The email delivery service that people actually like
"The email delivery service that people actually like"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
vs.

Startmail

Private email you can trust
"Private email you can trust"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
$15/moPricing$7/mo
No Postmark does not support storageStorage20 GB
10 MBAttachments25 MB
NoOpen-SourceNo
NoSandboxed Encryption ❌ Startmail claims to use a User Vault, but this statement has not been audited and their source code is closed-source
NoUnlimited DomainsNo
NoUnlimited AliasesNo
TTI TTI No
YesSMTPYes
NoIMAPYes
NoPOP3Yes
YesAPINo
NoE2EE ⚠️ Supported if both sender and recipient are using OpenPGP
NoOpenPGP ⚠️ Supports OpenPGP, but does not support WKD
NoWKD No

Email Service Screenshots

Closed-source

Postmark

Postmark is a closed-source email service. According to their website: The email delivery service that people actually like

Postmark is a closed-source email service.
Photo by Forward Email
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Closed-source

Startmail

Startmail is a closed-source email service. Their official description reads: Private email you can trust

Startmail is a closed-source email service.
Photograph by Forward Email
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Compare Postmark with 78 email services