Coldletter

Coldletter

Optosoftware inc.
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About

Coldletter is an email templating and automation platform built for product and engineering teams that need better control over the emails their applications send. The platform works on top of providers such as SendGrid, Postmark, Amazon SES, Mailgun, Resend, and SparkPost, allowing teams to keep their existing delivery stack. Users can design responsive, accessible, and dark-mode-safe email templates with a visual editor instead of hand-coding complex HTML or MJML. Coldletter also supports reusable blocks, typed variables, live previews, test sends, localization, version control, and approval workflows. Its automation tools let teams build email journeys with triggers, waits, branches, A/B testing, and delivery analytics. Coldletter helps teams design, automate, manage, and deliver product emails more reliably from one centralized workspace.

About

Ensure flawless email communication with the SMTP Debug Tool, a completely free and secure way to diagnose SMTP connection issues. This tool connects to your SMTP server, initiates a test session, and provides a detailed log of the interaction between servers. Whether you're using popular email services like SendGrid, Google SMTP, Elastic Email, UniOne or Mailgun, this tool simplifies troubleshooting and helps resolve sending errors. With end-to-end encryption, your information remains private and secure. The tool doesn’t store any session logs or credentials, and you can further enhance security by changing your password after testing or using the optional “SMTP Blackhole” feature.

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Audience

Coldletter is designed for product teams, engineering teams, lifecycle marketers, SaaS companies, and developers that need a centralized platform for designing, automating, versioning, and sending product emails through existing providers

Audience

Developers, startups, email marketers

Support

Phone Support
24/7 Live Support
Online

Support

Phone Support
24/7 Live Support
Online

API

Offers API

API

Offers API

Screenshots and Videos

No images available

Screenshots and Videos

No images available

Pricing

$0
Free Version
Free Trial

Pricing

$0
Free Version
Free Trial

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Training

Documentation
Webinars
Live Online
In Person

Training

Documentation
Webinars
Live Online
In Person

Company Information

Optosoftware inc.
Founded: 2025
Canada
coldletter.com

Company Information

SMTP Debug Tool
Founded: 2019
Cyprus
smtpdebug.com

Alternatives

SendGrid

SendGrid

Twilio SendGrid

Alternatives

SendGrid

SendGrid

Twilio SendGrid
Debug Mail

Debug Mail

DebugMail.io
HELO

HELO

Beyond Code
Mailcatch

Mailcatch

Felis Studio

Categories

Categories

Integrations

SendGrid
Amazon SES
Elastic Email
Mailgun
Postmark
UniOne

Integrations

SendGrid
Amazon SES
Elastic Email
Mailgun
Postmark
UniOne
Claim Coldletter and update features and information
Claim Coldletter and update features and information
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Claim SMTP Debug Tool and update features and information