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Warmup Inbox vs Sendmux

A side-by-side comparison built from both listings. Blank cells mean the company has not given that detail; we never guess.

Warmup Inbox compared with Sendmux
DetailWarmup Inbox logo Warmup InboxSendmux logo Sendmux
What it doesEmail warmup service that improves deliverability and sender reputation Email API that gives AI agents a real inbox with send, receive, and routing capabilities
StageNot given Not given
FoundedNot given Not given
Based inSK Not given
Pricing modelFreemium Not given
PricingNot given Free: $0/team/month with 2 mailboxes, $1 usage credit, 50 recipients/day. Pro: $7/team/month + usage. Connected outbound: $0.50/1,000 accepted recipients. Managed sending: $0.75/1,000. Inbound: $0.50/1,000 mailbox deliveries. Storage: $0.02/GB/month.
Key features
  • Sync inbox to network of 30,000+ real inboxes
  • Automated interactions: replies, marking as important, removing from spam
  • Email health monitoring and reports
  • Spam filter monitoring
  • Email reputation check
  • Outreach sequences
  • Custom warm up settings (Pro plan)
  • Scheduled warm up (Pro plan)
  • Multi-provider outbound routing with weighted distribution
  • Dedicated inboxes with clean JSON parsing
  • Mailbox-scoped API keys
  • Signed webhooks and Server-Sent Events
  • Per-provider quotas at multiple time windows
  • Unified inbox view for all agent mailboxes
  • Message parsing reducing LLM token usage by 80%
What makes it different
  • 30,000+ real inboxes used by real people in the network
  • One of the first companies to offer email warmup services
  • Simple and straightforward platform and pricing
  • Can help resurrect domains with poor reputation
  • Brings your own email providers with automatic routing and failover instead of platform lock-in
  • Reduces LLM token consumption by up to 80% with structured JSON parsing and content cleaning
  • Multi-tenant architecture with mailbox-scoped credentials for agent isolation
Community votes00
DR (Domain Rating by Ahrefs)61 −1 (down) since last check39 no change since last check
Trust Flow (Majestic)2928
Citation Flow (Majestic)4635
Referring domains (Majestic)1824241

3 details filled in for both companies.

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