Company Registry
The companies email runs on.
The mailbox providers, sending platforms, and tools referenced across the Email Almanac, each with a plain-language note on what it is. Spot something we should add or correct? Get in touch.
Esp (91)
Marketing platform best known for email campaigns, automation, and audience management for small businesses.
Twilio-owned email delivery platform for transactional and marketing email at scale.
Email marketing platform aimed at small businesses, offering campaigns, automation, and templates.
Email marketing platform offering drag-and-drop campaigns, automation, and analytics.
Marketing and transactional email platform, formerly Sendinblue, with SMS and CRM features.
Marketing automation platform focused on email and SMS for ecommerce brands.
Customer experience automation platform combining email marketing, automation, and CRM.
Inbound marketing, sales, and CRM platform with built-in email marketing tools.
Developer-focused email API for sending, receiving, and tracking transactional email.
Amazon's cloud-based email sending service for transactional and bulk email.
Transactional email service focused on fast, reliable delivery and detailed analytics.
Cloud email delivery platform for transactional and marketing email, now part of Bird.
Email testing and sending platform for developers to inspect and deliver email safely.
Email marketing platform built for online creators, now branded Kit.
Email marketing platform for small businesses, offering autoresponders and newsletter tools.
Email marketing and automation platform with landing pages and webinar tools.
Ecommerce marketing automation platform focused on email and SMS.
Email marketing platform offering newsletters, automation, and landing pages for small businesses.
Ecommerce marketing automation platform combining email, SMS, and push notifications.
Email marketing and automation platform, part of the Sitecore group.
Email marketing platform offering campaigns, automation, and responsive templates.
Email delivery and marketing platform offering an API and SMTP relay for bulk sending.
Cloud SMTP relay service for reliable transactional and bulk email delivery.
Transactional email add-on for Mailchimp, built on its delivery infrastructure.
Email service for marketing and transactional messages, part of the Sinch group.
Email delivery platform for transactional and marketing email with deliverability tools.
Salesforce's enterprise marketing platform for email, mobile, and cross-channel campaigns.
Cross-channel marketing platform for email, SMS, push, and in-app messaging.
Automated messaging platform for email, push, and SMS driven by customer data.
Customer messaging platform combining live chat, email, and support automation.
Adobe-owned marketing automation platform for email, lead management, and campaigns.
Customer engagement platform for cross-channel messaging across email, push, and in-app.
Cloud communications platform providing APIs for SMS, voice, and email messaging.
Low-cost email marketing platform for newsletters and automations.
Email and SMS marketing platform for small businesses.
Self-hosted newsletter application that sends through Amazon SES.
Email newsletter plugin for WordPress websites.
Open-source marketing automation platform.
Self-hosted, open-source newsletter and mailing list manager.
Open-source email newsletter and campaign manager.
Spanish email and SMS marketing platform.
French email and SMS marketing platform.
Email marketing platform with advanced automation and testing.
Email marketing tool for small businesses and nonprofits.
Email marketing platform for growing brands, part of Marigold.
Email marketing platform aimed at small businesses.
Email marketing and automation platform for mid-market senders.
Multichannel marketing automation platform including email.
Email marketing front end that sends across multiple delivery providers.
Marketing and commerce platform with email automation.
Marketing automation platform, now part of Constant Contact.
Marketing automation platform for mid-size businesses.
B2B marketing automation platform from Oracle.
Cross-channel campaign management platform from Oracle.
Cross-channel campaign management platform from Adobe.
Marketing automation platform, formerly IBM Watson Marketing.
Marketing automation platform, now part of Marigold.
Omnichannel customer engagement platform owned by SAP.
Commerce experience platform that includes the Exponea engagement engine.
Cross-channel marketing and data platform for enterprise senders.
Customer data and cross-channel marketing platform.
Retail and media email personalization platform, part of Marigold.
Retail-focused cross-channel marketing automation platform.
Cross-channel marketing platform, part of Marigold.
Relationship marketing group behind Emma, Sailthru and Cheetah.
Data-driven marketing cloud including email campaigns.
Retail customer data and marketing platform.
Cross-channel marketing automation platform.
B2B marketing automation from Salesforce, now Account Engagement.
Small business CRM and marketing automation, formerly Infusionsoft.
CRM and marketing automation platform for small businesses.
Email and SMS marketing platform for ecommerce.
Marketing automation and analytics platform, formerly Autopilot.
Behavioral email marketing and messaging platform.
Newsletter publishing and growth platform for creators and media.
Publishing platform for paid and free email newsletters.
Open-source publishing platform with built-in email newsletters.
Minimalist newsletter tool for writers and developers.
Email platform for software companies covering marketing and transactional email.
Email marketing tool focused on design-forward templates.
Email platform for building interactive AMP emails.
Multichannel marketing platform covering email, SMS and chatbots.
Email and SMS marketing platform popular in Eastern Europe.
Omnichannel marketing automation platform.
Email marketing platform with generous free sending tiers.
Omnichannel marketing automation platform for mid-market senders.
Marketing automation product from Freshworks.
Email marketing tool built into the Shopify commerce platform.
Creator platform for courses and memberships with built-in email.
Email marketing platform aimed at small businesses and nonprofits.
Email delivery and campaign platform with deliverability services.
Provider (53)
Google's consumer email service, the largest mailbox provider worldwide with billions of active inboxes.
Microsoft consumer email service. Originally a separate brand, now merged into Outlook.com, but @hotmail.com addresses still exist and the brand still appears in deliverability discussions.
Google's business email and productivity suite offering custom-domain Gmail alongside Docs, Drive, and Calendar.
Yahoo's free consumer webmail service, one of the oldest and largest mailbox providers.
Microsoft's consumer webmail service, successor to Hotmail and the home of Outlook.com inboxes.
Microsoft's business email and productivity suite providing Exchange Online mailboxes with the Office apps.
Apple's built-in email client bundled with Mac, iPhone, and iPad devices.
Swiss end-to-end encrypted email service focused on privacy and security.
Zoho's business email service with custom domains, part of its wider productivity suite.
AOL's free consumer webmail service, now running on Yahoo's mail infrastructure.
Apple's cloud-based email service tied to Apple IDs and iCloud accounts.
Independent paid email provider based in Australia, focused on speed and privacy.
German end-to-end encrypted email service focused on privacy, now branded Tuta.
German free webmail provider offering consumer email accounts across Europe and beyond.
Free webmail service operated by the Russian technology company Yandex.
Free webmail provider offering a wide choice of custom domain endings.
Privacy-focused email service based in Belgium with built-in encryption.
Encrypted email provider aimed at healthcare and small business users.
Privacy-oriented, ad-free email provider based in Germany.
German secure email and office provider for individuals and businesses.
Privacy-focused paid email service from the makers of Startpage.
Norwegian email provider focused on privacy and sustainability.
Swiss-hosted email and groupware service built on open-source Kolab.
Major Russian free webmail service and internet portal.
Russian webmail service and internet portal.
Webmail service operated by the Chinese technology company Tencent.
Chinese webmail provider running the 163.com and 126.com domains.
Webmail service run by the Chinese media company Sina.
Webmail service from South Korea's largest search portal, Naver.
South Korean webmail service operated by Kakao's Daum portal.
Indian webmail service operated by Rediff.com.
Italian webmail service and internet portal.
Italian webmail service operated by Italiaonline.
Webmail service provided by the French telecom operator Orange.
French webmail service run by the national postal service La Poste.
German webmail provider, part of United Internet alongside GMX.
German webmail service operated by Deutsche Telekom.
Email service for Comcast Xfinity internet subscribers in the US.
Brazilian webmail service from the UOL internet portal.
Portuguese webmail service operated by the SAPO portal.
Czech webmail service operated by the Seznam.cz portal.
Polish webmail service from the Onet portal.
Polish webmail service operated by Wirtualna Polska.
Polish webmail service from the Interia portal.
Managed business email and calendar service from Amazon Web Services.
Business email hosting built for small businesses and professionals.
Business email service for entrepreneurs, including a free domain option.
Opinionated email service and client from 37signals.
Open-source email forwarding and hosting service.
Open-source email alias service, part of Proton.
Open-source email aliasing service for protecting your real address.
Free email forwarding service that strips trackers, from DuckDuckGo.
Email masking service from Mozilla that hides your real address.
Infrastructure (41)
Web infrastructure and security company providing DNS, CDN, and email routing services.
Amazon's cloud computing platform hosting infrastructure, storage, and email services like SES.
High-volume commercial mail transfer agent for enterprise email delivery, from the SparkPost team.
Open-source mail transfer agent built for high-volume email delivery.
Widely used open-source mail transfer agent for routing and delivering email.
Open-source mail transfer agent common on Unix systems, especially cPanel hosting.
Open-source high-performance SMTP server written in Node.js.
Microsoft's enterprise mail server for email, calendaring, and contacts.
Developer-focused API for sending transactional and marketing email.
Transactional email and SMS API from the MailerLite group.
Fast, privacy-focused transactional email delivery service.
Long-running SMTP relay and email delivery service.
SMTP relay and transactional email service.
Marketing and transactional email platform, formerly Pepipost.
Email API and delivery under the Sinch communications group.
Customer engagement platform, formerly MessageBird, with email and SMS.
Notification infrastructure API spanning email and other channels.
Notification infrastructure that routes email and in-app messages.
Open-source notification infrastructure including email.
Notification infrastructure platform covering email and other channels.
Programmable MTA for email service providers and enterprises.
High-volume outbound MTA software.
Self-hosted email delivery software and MTA.
Classic secure MTA written by Daniel J. Bernstein.
Free SMTP server implementation from the OpenBSD project.
Popular open-source IMAP and POP3 server.
Docker-based, open-source mail server suite.
Dockerized, open-source email server suite.
Open-source mail server deployment for major Linux distributions.
Open-source mail server for sending and receiving at scale.
Modern open-source mail server supporting JMAP, IMAP and SMTP.
Open-source and commercial email and collaboration server.
Windows email server for small and midsize businesses.
Free, open-source email server for Windows.
Open-source mail hosting and management platform.
Open-source Java email server and mail application platform.
Email server and collaboration suite for businesses.
Open-source DKIM signing and verification filter.
Open-source DMARC filtering and reporting software.
Outbound email delivery and filtering for hosting providers.
Commercial MTA for high-throughput, self-hosted email delivery on Linux, private cloud, or bare metal, with real-time delivery dashboards and granular routing, throttling, retry, and TLS controls.
Tool (40)
Platform for deploying and monitoring DMARC email authentication with reporting dashboards.
Web toolset for diagnosing email, DNS, and blocklist issues.
Free web tool that scores an email message's spam risk and configuration.
Email testing and analytics platform for previewing and optimizing campaigns across clients.
Email testing platform for previewing, checking, and optimizing campaigns before sending.
Data quality and email deliverability company, owner of BriteVerify and Everest.
Validity's free service rating a sending IP's reputation on a 0 to 100 scale.
Deliverability testing platform for inbox placement, spam checks, and DMARC monitoring.
Google's free dashboard showing sender reputation, spam rates, and delivery data for Gmail.
Platform for DMARC, SPF, and DKIM management with reporting and monitoring.
Email authentication platform automating DMARC, SPF, and DKIM enforcement.
Email verification and deliverability service for cleaning lists and reducing bounces.
Email verification service for cleaning lists and reducing bounce rates.
Email finder and verification tool for building and checking professional email lists.
Drag-and-drop email template builder with ESP integrations.
No-code email and landing page design suite.
No-code email and landing page builder for enterprise teams.
Email production platform for building and collaborating on templates.
Collaborative email template builder for teams.
Drag-and-drop email template editor.
Embeddable drag-and-drop email and page builder for apps.
Code editor built specifically for HTML email development.
Open-source markup framework for coding responsive email.
Framework for building HTML emails with Tailwind CSS.
Responsive email framework from Zurb.
Email builder from Designmodo for creating modular templates.
Email content management and template collaboration platform.
Email and landing page creation platform for enterprise teams.
Free email testing tool from Litmus for sending test messages.
Email and SMS testing service for QA and development teams.
Open-source email testing tool for developers.
Open-source email testing tool that captures outgoing mail in development.
Public disposable inbox service used for testing email flows.
Email API for testing and automation.
Curated gallery of email designs for inspiration.
Searchable archive of marketing emails from brands.
Email marketing intelligence and competitor tracking, part of Validity.
Reference for HTML and CSS support across email clients.
Automatic SPF flattening service to stay under the lookup limit.
AI email-review platform that scores creative, copy, CTAs, accessibility, and deliverability, and benchmarks competitor campaigns.
Security (31)
Nonprofit organization providing threat intelligence and reputation data used in email filtering.
Security company offering email protection, firewalls, and data protection appliances and services.
Spam and open relay blocking system providing DNS-based reputation lists.
Cisco-operated service that processes spam reports to build a real-time blocking list.
Network abuse handling and threat intelligence company serving ISPs and hosting providers.
Proofpoint-owned messaging security provider offering spam and threat filtering for carriers.
Open-source Apache anti-spam platform using content rules and scoring to filter email.
Open-source spam filtering system offering fast, rule-based email scanning.
Enterprise security company offering email protection, threat detection, and compliance tools.
Cloud email security and resilience platform for threat protection and archiving.
Anti-spam blocklist focused on hard-to-detect spam sources.
Blocklist of domains found in unsolicited messages.
Realtime URI blocklist used to filter spam by its links.
Provider of DNS blocklists and email filtering data.
Network-based anti-spam blocklist operator.
Passive Spam Block List, a community-driven blocklist.
Collection of blocklists targeting spam and misconfigured mail servers.
Reputation and blocklist data provider for email filtering.
Cisco Talos threat intelligence and IP or domain reputation lookup.
Email security and threat protection provider.
Email security gateway from TitanHQ.
Email security gateway from Fortinet.
Email security gateway from Cisco, formerly IronPort.
Cloud email security from Trend Micro.
Cloud email security from Sophos.
Email authentication and anti-phishing, now part of Fortra.
AI-based email security platform that stops advanced attacks.
Email security platform focused on phishing detection and response.
Email security platform that protects mailboxes after compromise.
Programmable email security platform with a detection rule engine.
Cloud email security and archiving, formerly SpamExperts.
Hosting (24)
Domain registrar and web host that also sells business email inboxes.
Web hosting provider that bundles domain-based email mailboxes.
Domain registrar offering private email hosting on customer domains.
Web host and registrar, formerly 1&1, selling domain email and Microsoft 365.
Budget web host offering domain-based email through Hostinger and Titan.
Web hosting company that provides mailbox hosting on customer domains.
Shared web host bundling email accounts with hosting plans.
Managed web host offering domain-based email hosting.
Web hosting provider offering email hosting on customer domains.
US web host bundling business email with hosting plans.
Long-running registrar and host that sells business email.
Domain registrar offering simple domain-based email mailboxes.
Domain registrar offering low-cost email hosting add-ons.
European cloud host and registrar offering domain email services.
Domain registrar and host providing mailboxes on customer domains.
Domain registrar offering email hosting on registered domains.
Low-cost domain registrar with email hosting add-ons.
Eco-focused web host bundling domain-based email.
Website builder that resells Google Workspace email on custom domains.
Website builder offering business email through Google Workspace.
UK domain registrar and host selling domain-based email.
Hosted business email service from Rackspace Technology.
Swiss email hosting with flat-rate, domain-based mailboxes.
Low-cost email hosting with unlimited domains and addresses.
Validation (23)
Email verification service that flags risky and undeliverable addresses.
Email verification and list cleaning service.
Bulk email verification service priced per list.
Email verification API and bulk list cleaning service.
Email verification and finder platform.
Bulk email validation and list cleaning service.
Bulk email verification and list cleaning service.
Email verification API and bulk list cleaning service.
Email validation API and bulk verification service.
Real-time email verification and lead validation service.
Email verification service from Validity.
Data quality and identity verification provider including email checks.
Automated email verification that plugs into marketing platforms.
Email and phone verification service.
Bulk and real-time email verification service.
Bulk email verification and list cleaning service.
Email verification and inbox tools provider.
Email address intelligence and verification, formerly TowerData.
Email list hygiene and verification services.
Email list hygiene and verification service.
Email verification API and bulk checking service.
Email verification and hygiene service that flags traps and risky addresses.
Email verification API and bulk list cleaning service.
Deliverability (16)
Email deliverability monitoring and DMARC platform.
Deliverability, inbox placement and email intelligence platform.
Free spam test that checks deliverability before sending.
Free deliverability and spam-score testing tool.
Uptime and blacklist monitoring service for domains and IPs.
Inbox placement and deliverability monitoring platform.
Microsoft's Smart Network Data Services for monitoring IP reputation.
Yahoo's postmaster resources and sender reputation tools.
DMARC, SPF and DKIM monitoring and reporting platform.
Email security and DMARC platform behind OnDMARC and OnINBOX.
Managed DMARC and email authentication platform.
Automated DMARC, SPF and DKIM enforcement platform.
DMARC and network reporting monitor for domains.
DMARC reporting and SPF management service.
Email authentication monitoring and hardening service.
Free weekly DMARC monitoring reports from Postmark.
Client (12)
Free open-source email client from Mozilla for desktop mail, calendar, and contacts.
Desktop email client for Windows and Mac.
Desktop email and calendar client for Windows and Mac.
Cross-platform email client from Readdle.
Conversational email client and collaboration app.
Email client for Apple platforms.
Secure email client with encryption for Mac, iOS and Android.
Fast email client for professionals, built on Gmail and Outlook.
Shared inbox and email collaboration client for teams.
Shared inbox platform for customer-facing teams.
Text-based email client for Unix systems.
Lightweight open-source email client for Linux.
Organization (12)
European email certification program that sets sender standards.
Email marketing professional community, part of the ANA.
Association of National Advertisers, parent of the Email Experience Council.
Private community of email marketing professionals.
Nonprofit supporting women working in the email industry.
Anti-Phishing Working Group, a coalition fighting email-based fraud.
Nonprofit promoting email authentication and internet security.
Industry group behind the BIMI logo standard for email.
French public-private partnership for reporting and fighting spam.
Nonprofit supporting open development and use of the internet.
Body that coordinates the internet's domain name system.
Deliverability news and reference blog by Al Iverson.
Standards (5)
Internet Engineering Task Force, the body that develops core internet standards including email.
Messaging, Malware and Mobile Anti-Abuse Working Group, an industry body fighting online abuse.
Industry resource and working group behind the DMARC email authentication standard.
Body that coordinates the DNS root, IP addressing and protocol assignments.
Informational site for the DomainKeys Identified Mail standard.
Consultancy (3)
Email deliverability consultancy led by Laura Atkins.
Email deliverability consultancy and monitoring provider.
Email deliverability and data services company.