MailerSend vs Proton Mail Comparison (2025)

What are the differences between MailerSend and Proton Mail?

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 MailerSend.

Email Service Comparison

20 facts in comparison
MailerSendvs.Proton Mail

MailerSend

Intuitive email API and SMTP
"Intuitive email API and SMTP"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
vs.

Proton Mail

Secure email that protects your privacy
"Secure email that protects your privacy"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
$288/yrPricing$3.99/mo
No MailerSend does not support storageStorage15 GB
25 MBAttachments25 MB
NoOpen-Source❌ Proton Mail claims to be open-source, but their back-end actually is closed source
NoSandboxed Encryption No
NoUnlimited DomainsNo
NoUnlimited AliasesNo
NoTTI No
YesSMTP❌ Requires you to download Proton Mail Bridge and forces vendor lock-in
NoIMAP❌ Requires you to download Proton Mail Bridge and forces vendor lock-in
NoPOP3❌ Proton Mail does not support POP3
YesAPINo
NoE2EE ⚠️ Proton Mail rewrites your emails
NoOpenPGP Yes
NoWKD Yes

Email Service Screenshots

Closed-source

MailerSend

MailerSend is a closed-source email service. Its description from its website is: Intuitive email API and SMTP

MailerSend is a closed-source email service.
Photo by Forward Email
Visit Website
Closed-source

Proton Mail

Proton Mail is a closed-source email service. Their official description reads: Secure email that protects your privacy

Proton Mail is a closed-source email service.
Photo by Forward Email
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Compare MailerSend with 78 email services