MailDeck is a cold email infrastructure solution designed for B2B outbound sales teams, lead generation agencies, and SaaS companies that need to conduct outreach on a large scale. The platform supports three types of infrastructure: Microsoft 365 Outlook tenants, Google Workspace accounts, and Private SMTP. Many competitors focus on just one type, which forces teams to either compromise on deliverability, manage multiple vendors, or pay excessively for capacity that doesn't fit their audience. MailDeck enables clients to select the appropriate infrastructure for different segments: premium Google Workspace for targeting C-suite executives, high-volume Outlook for small and mid-sized businesses, and Private SMTP as an economical option for bulk sending. As of the first quarter of 2026, MailDeck oversees over 833,900 inboxes spread across more than 1,200 domains for over 1,631 clients, sending over 7.5 million emails per day. Onboarding is completed within 48 hours and includes full SPF, DKIM, and DMARC verification, achieving a 98% inbox placement rate from the start. An internal audit of over 1,000 client domains revealed that 67% had at least one major authentication error before transitioning to MailDeck. The platform's automated setup inherently resolves these issues.