# MailDeck

> Scalable Cold Email Infrastructure

- Canonical listing: https://agencysource.com/agencies/maildeck
- Location: San Francisco, CA
- Categories: [Lead Generation](https://agencysource.com/categories/lead-generation), [Email & Lifecycle Marketing](https://agencysource.com/categories/email-marketing), [Cold Email](https://agencysource.com/categories/cold-email)
- Services: Email Marketing
- Team size: 2 - 9
- Hourly rate: Undisclosed
- Minimum project: Undisclosed
- Founded: 2025
- Website: https://maildeck.co
- Listing: Not yet claimed
- Agency Source rating: no Agency Source reviews yet

## About

MailDeck is a cold email infrastructure provider built for B2B outbound sales teams, lead generation agencies, and SaaS companies running outreach at scale. The company operates across three infrastructure types under one platform: Microsoft 365 Outlook tenants, Google Workspace accounts, and Private SMTP. Most competitors specialize in just one, forcing teams to compromise on deliverability, juggle multiple vendors, or overpay for capacity they cannot match to their audience. MailDeck lets clients deploy the right infrastructure for each segment: premium Google Workspace for C-suite outreach, high-volume Outlook for SMB and mid-market, and Private SMTP as a cheap volume buffer.

As of Q1 2026, MailDeck manages 833.9K+ inboxes across 1,200+ domains for 1,631+ clients, with platform-wide volume of 7.5M+ emails sent per day. Onboarding completes in 48 hours with full SPF, DKIM, and DMARC verification, delivering a 98% inbox placement rate from day one. An internal DNS audit across 1,000+ client domains found 67% had at least one critical authentication error before migrating to MailDeck. These are errors the platform's automated setup eliminates by default.

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Source: Agency Source, https://agencysource.com/agencies/maildeck. Ratings and reviews come only from reviews submitted and moderated on Agency Source; agencies cannot pay for rank.