Companies using Postmark and Userlist

5 companies in our data have public evidence for both Postmark and Userlist, and 5 name both in their own subprocessor list. Each company below links to the source for every claim. Our coverage is partial, so this is not everyone.

5companies use both

1%of Postmark users

38%of Userlist users

5name both as subprocessors

Companies using one are 23 times as likely as the average company in our data to show evidence of the other.

The companies

Strongest evidence first: a company naming both in its own subprocessor list comes before one seen on its website or in job postings.

Subprocessor listPrivacy policyWebsiteJob postings

Company	Postmark	Userlist
GitDailiesgitdailies.comGitDailies provides pull request metrics, DORA dashboards, and alerts computed from GitHub metadata.Developer tools Productivity and collaboration
Honeybadgerhoneybadger.ioHoneybadger provides error tracking, logging, and application performance monitoring for web apps in production.Developer tools
SavvyCal Appointmentssavvycal.appSavvyCal Appointments provides a scheduling engine and API that computes availability, enforces scheduling rules, and books appointments atomically.Healthcare
SavvyCalsavvycal.comSavvyCal provides scheduling links that let recipients overlay their own calendar to find a meeting time.Productivity and collaboration
SignWellsignwell.comSignWell provides legally binding electronic signatures for sending, signing, and tracking documents, and offers a REST API for embedding signing workflows into products.

The two technologies

Postmark

by ActiveCampaign · Email and communications

Postmark is an email delivery service that sends transactional emails for applications through its API and SMTP service. It is used by developers and companies to send emails such as order notifications and account messages, with the page describing it as focused on inbox deliverability.

Summarized from postmarkapp.com on 8 Nov 2026.

1% of the 387 companies we see using Postmark also show the other.

All 387 companies using Postmark 342 name it as a subprocessor More in Email and communications

Userlist

Email and communications

Userlist is an all-in-one email marketing platform. It is used to automate email marketing and messaging for SaaS companies.

Summarized from userlist.com on 8 Nov 2026.

38% of the 13 companies we see using Userlist also show the other.

All 13 companies using Userlist 11 name it as a subprocessor More in Email and communications

Industries

Among the companies above, by our own classification of their homepage.

Developer tools2 Productivity and collaboration2

Other pairs

Companies with their own evidence for both.

More with Userlist

Cloudflare13companies

Amazon Web Services10companies

Google Workspace10companies

Stripe10companies

Google Tag Manager6companies

Help Scout6companies

Questions

How many companies use both Postmark and Userlist?

5 companies in StrataDB's data have public evidence for both, and 5 of them name both in their own subprocessor list, the strongest evidence we hold. Our coverage is partial, so the real number is higher.

Which companies use Postmark and Userlist?

GitDailies, Honeybadger, SavvyCal Appointments, SavvyCal and SignWell. Each one links to the evidence behind it.

How does StrataDB know a company uses Postmark and Userlist?

From four kinds of public evidence: subprocessor lists, privacy policies, website code and job postings. Each is kept apart with its source and the date we saw it. A company missing here means we found no evidence, not that it does not use them.

Find every company using Postmark and Userlist

See the full list with the source for each company, and run the same lookup for any technology from the API, Claude or your browser.

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