How do cold email tools work behind the scenes?

Cold email tools automate what would otherwise be manual, repetitive sending. Here's how they operate:

Mailbox connection: Tools connect to your email accounts using IMAP (to read replies) and SMTP (to send). They authenticate as you, making messages appear to come from your actual mailbox rather than a bulk sending system.

Sending management: They schedule messages throughout the day, spacing them to mimic human sending patterns. Many tools add random delays between sends.

Account rotation: To distribute volume, tools rotate across multiple connected mailboxes, sending some messages from each.

Sequence automation: If no reply is detected, the tool queues follow-up messages at configured intervals. Reply detection uses IMAP to scan for responses and pauses the sequence when one arrives.

Tracking: Open tracking uses pixel images; click tracking routes links through tracking domains. Both raise deliverability concerns and many senders disable them.

The goal is making automated sends look like individual, human-sent messages. Mailbox providers are increasingly sophisticated at detecting these patterns.