Rebelmail
Acquired14 known investors
API and platform for interactive emails with real-time analytics; acquired by Salesforce
Also known as EngageInbox · Rebel · Rebelmail · RebelMail
Investors · 14
Also in the syndicate · 10
Company profile
researched Aug 2026Rebelmail, later renamed Rebel, developed technology that turned marketing emails into interactive experiences. Rather than redirecting recipients to a website, its product embedded form fields, product galleries, quizzes, surveys, appointment booking, review collection and checkout directly inside the email message, positioning the inbox as an extension of a brand's website or app. The company described its aim as powering secure interactivity inside emails for e-commerce and SaaS companies, with its first product enabling one-click checkout inside emails for e-commerce retailers.
The company offered both a Mail product and an API-based solution. In June 2017 it rebranded from Rebelmail to Rebel and launched Rebel Shop, which allowed consumers to complete a purchase from within an email; the flow relied on payment credentials previously stored with the retailer or with another retailer in the Rebel network, so card details were not entered in the message itself, and the company said its payment system was PCI compliant. Co-founder Joe Teplow framed email as "the last owned channel" for retailers and said the company's ambitions extended beyond email to other customer-facing channels. In October 2018, Salesforce agreed to acquire Rebel to strengthen its Marketing Cloud, with Rebel's services to be integrated into that platform; terms were not disclosed.
Founding story
Co-founders Joe Teplow and Trever Faden, who had participated in the Y Combinator accelerator program, developed the concept together. Teplow had previously run a not-for-profit email project in which subscribers donated 25 cents a day to a choice of charities; it grew from about ten friends to more than 300 subscribers and donated more than $30,000 in a year, with roughly 75% daily open rates and 65% click rates, which drew Teplow to email as an interface. Faden had built a project that embedded form fields in email; after receiving one such message, Teplow mocked up a J. Crew campaign with a form field and instant checkout, and the pair then tested interactive emails with small e-commerce companies before raising outside capital.
Business model
Rebel sold interactive email technology to businesses, offering Mail and API products that brands and their email service providers used to add interactive and transactional capabilities to marketing campaigns. Following the 2018 seed round, the company said it would use the capital to expand its enterprise offerings.
Traction
The company worked with large brands including Home Depot, eBay, WeWork and Diane von Furstenberg, and cited Dollar Shave Club, L'Oreal and HelloFresh among brands using its Mail and API solutions. One customer reported a 55% increase in customer reviews after using the product. Total disclosed funding was about $3 million as of the 2018 acquisition.
Latest developments
On October 5, 2018, Salesforce agreed to acquire Rebel, with the team joining Salesforce Marketing Cloud and Rebel's API-based services to be integrated into the platform. Deal terms were not disclosed.
▸Full profile — market position, technology, go-to-market, geography, history, risks & controversies
Market position
Rebel operated in email marketing technology, an area where Salesforce competes with Adobe and where inbox providers such as Microsoft Outlook and Google Gmail have added native features including in-email payments. Its interactive checkout approach had been characterized in press coverage as a long-sought capability for email marketers.
Rebel's product completed actions such as browsing, quizzes, reviews and purchases inside the email itself rather than redirecting recipients to a website, and it delivered these capabilities through an API that could be used alongside existing email service providers.
Technology
An API and platform that renders interactive components inside email clients, supporting form fields, galleries, quizzes, surveys, appointment booking, review submission and in-message payment processing. The one-click checkout used payment information previously stored by the retailer or by another retailer in the Rebel network so that card data was not entered inside the email, and the company stated the payments system was fully PCI compliant.
Go-to-market
Rebel sold directly to brands and retailers with an enterprise-focused platform, and integrated with a range of email service providers; at the time of the acquisition its partners included Oracle, SendGrid, Adobe, IBM, SailThru and Salesforce.
E-commerce and SaaS companies and enterprise brands running email marketing programs. Named customers and users included Home Depot, eBay, WeWork, Diane von Furstenberg, Dollar Shave Club, L'Oreal and HelloFresh.
Geography
Initially based in Washington, D.C. at the time of its 2014 seed round; later headquartered in New York, New York.
History
The company was originally called EngageInbox and launched its interactive email product in early 2014. Boldstart Ventures records a first check in April 2014, and a $2 million seed round was announced in June 2014. The company rebranded from Rebelmail to Rebel in June 2017 alongside the launch of in-email one-click checkout, raised a $3 million seed round announced in May 2018, and agreed to be acquired by Salesforce in October 2018, joining the Salesforce Marketing Cloud organization.
Risks & controversies
At the time of the acquisition it was unclear whether Rebel's standalone business would be wound down, whether it would continue integrating with third-party email service providers, and customers had not been informed of the outcome; neither Salesforce nor Rebel commented on those points. Competition included native interactive and payment features added by Microsoft Outlook and Gmail and alternatives offered through incumbent direct marketing providers.
Compiled by commissioned research from 9 cited public sources — announcements, filings, and press listed under research sources below.
Key figures
latest reportedCompany-reported or press-reported figures, each dated to when it was claimed — not independently audited.
Timeline · 5
launches, deals, and filingsSalesforce signed an agreement to acquire Rebel and said the startup's API-based interactive email services would be integrated into Salesforce Marketing Cloud. Terms were not disclosed.
Salesforce signed an agreement to acquire Rebel, developer of interactive email and API solutions, with the team joining Salesforce's Marketing Cloud, which will integrate Rebel's API-based services. Terms of the deal were not disclosed.
Rebel closed a $3 million seed round with Courtside Venture Capital, Sinai Venture Capital and Wisdom Venture Capital, to be used to expand its enterprise offerings.
$3M source ↗
The company rebranded from Rebelmail to Rebel and added one-click checkout, letting consumers complete purchases inside an email rather than clicking through to a retailer's site. Payment details must have been previously stored with the retailer or another retailer in the Rebel network; the company states its payments system is PCI compliant.
The interactive email startup, formerly called EngageInbox, raised a $2 million seed round co-led by Vaizra and Boldstart, with Lerer Ventures, Box Group, Vayner RSE and angel investors participating. Founders Joe Teplow and Trever Faden said the funds would be used to hire and to run campaigns for larger e-commerce companies.
$2M source ↗
Dated company events from announcements, filings, and press; legal rows summarize public dockets and regulator releases.
▸Research sources · 9
primary sources listed
- RebelMail Grabs $2M in Seed fundingvcnewsdaily.com · web
- Rebel Mail — Marketing & Adtechf4.fund · web
9 public sources were cited for this profile; the first-party ones are listed here.
Frequently asked questions
- What does Rebelmail do?
- Rebel (formerly Rebelmail) built API-based interactive email for brands and was acquired by Salesforce in 2018.
- Who are Rebelmail's investors?
- Rebelmail's investors include boldstart ventures, Courtside Ventures, Outbound Ventures, The Chernin Group (TCG Crypto).