EmailWarmup vs InboxWarm.ai

EmailWarmup is a web and API service that uses AI-generated conversations and automated engagement to warm mailboxes for cold-email sending. Connected mailboxes pair in both directions with active peers, exchanging messages inside the network. AI creates subjects and replies with changing topics and tones, retaining a [WARMUP] subject tag. Slow, medium, and fast schedules gradually raise sending volume over several days. Supported engagement includes threaded replies, reads, stars, spam-folder rescue, and delivery checks. Gmail connects through OAuth, while SMTP/IMAP credentials are also supported; the maker says credentials are encrypted at rest and personal email content is not read or stored. Account data is retained while an account is active and deleted within 30 days after account deletion. A free Community plan lists one mailbox and 10 warmup emails per day. Paid plans start with Starter at $19 a month; Growth is $49 a month and Agency is $149 a month. EmailWarmup does not send outreach campaigns, repair blocklisted domains, or guarantee inbox placement.

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.