MailStrike vs WarmEnvelopes

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.

WarmEnvelopes is a web service that schedules genuine warm-up emails from a configured domain through the user’s Resend account. Messages go to inboxes the user controls, or whose owners have consented, to build sending history. Setup requires a verified sending domain and a Resend API key, with a separate key stored for each domain. A scheduler runs every 30 minutes and spreads the daily target across the day. Pro users can set starting volume, daily increases, and a maximum. The library contains more than 1,000 independently written messages in several languages, varying templates and sender names. Each send records its sender, template, delivery status, and errors, while the dashboard shows daily progress. The Free plan costs 0.00 EUR and permits four emails per day per domain across up to 10 domains. Pro costs €9 a month and supports up to 1,000 daily emails. A separate checker reviews SPF, DKIM, DMARC, MX, and blocklist status.