EmailWarmup vs MailStrike

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.

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.