InboxWarm.ai vs SendScale Email Warmup

InboxWarm.ai automatically warms Gmail, Outlook, and SMTP inboxes to build sender reputation, improve inbox placement, and reduce spam placement. It sends, opens, and replies to warmup messages using contextual replies generated by large language models and human-like sending patterns. InboxWarm describes its seed network as private and made up of real inboxes. Its spam recovery feature marks warmup messages as not spam and moves them to the primary inbox when they land in spam. Supported setups include Gmail, Outlook, SendGrid, Amazon SES, Mailgun, Yahoo, and custom SMTP/IMAP. Plans include SPF, DKIM, and DMARC domain-health monitoring and real-time inbox-placement tracking. Every plan includes a public REST API with 30 endpoints; the default rate limit is 20 requests per minute per API key. Monthly prices range from $15 a month for one mailbox to $5 a month for 51–100 mailboxes, with up to 100 warmup emails per inbox per day on those listed tiers. A 10-day trial covers one email account without a credit card.

SendScale Email Warmup is a service for warming email accounts and building sender reputation for cold outreach. It connects Google Workspace and Microsoft 365 inboxes through OAuth, then uses AI to exchange unique messages between accounts in a private network SendScale says contains more than one million inboxes. The service says its system opens and scrolls through messages and replies in human-style language. If a warmup email lands in spam, SendScale says it moves the message out, marks it important, and replies. A dashboard tracks daily sends and replies, spam-versus-inbox placement trends, and readiness. SendScale recommends 14 days for new domains and says the dashboard indicates when warmup is complete; warmup can continue at lower volume while campaigns run. The service also describes account rotation for load balancing and a Master Smartbox for consolidating replies. Its free plan includes pre-warmed inboxes, warmup tools, in-product conversational guidance, and campaign access. Paid plans start at $28/mo billed annually. The privacy policy places database servers exclusively in the European Union and describes industry-standard security measures.