InboxWarm.ai vs MailStrike

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.

MailStrike is an email deliverability platform for mailbox warming, placement testing, and seed lists for B2C senders. AI personas create and reply to email threads using a company's description and industry. Its warming network exchanges threads among business mailboxes while excluding spammers, free-mail senders, and dodgy sites. On connection, the service checks SPF, DKIM, DMARC, and MX records and identifies missing values. Google Workspace and Microsoft 365 connect through OAuth; other providers use IMAP and SMTP with an app password. Warming reaches full volume by day 21 and then continues at a maintenance volume. Seed lists monitor placement and can interact with messages; setup requires one DNS TXT record for domain verification. A free deliverability test reports inbox, promotions, or spam placement and scores spam signals without requiring a card. MailStrike runs on the web and through an API. Paid plans start at $18/mo (annual); there is no free plan, but a free trial is available.