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The Ballast blog.
Cold email that lands: SPF, DKIM and DMARC, sending limits, follow-ups and replies. Written by the people building Ballast, with the numbers we checked.
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Gmail Sending Limits for Cold Email in 2026
Gmail's real sending limits: 500 a day on free Gmail, 2,000 on Google Workspace, plus the recipient caps. What they mean for cold email, and a safe daily number.
Read the guideCold email8 min read
Cold Email Follow-Up: How Many, When, and What to Write
How to follow up on a cold email: how many follow-ups to send, how many days to wait between them, what each one should say, and when to stop. With examples.
AlexFounderRead articleGuides8 min read
List-Unsubscribe Header: How One-Click Unsubscribe Works
Set up the List-Unsubscribe header for one-click unsubscribe (RFC 8058): the two headers, the POST endpoint, DKIM signing, and what Gmail and Yahoo check. With code.
AlexFounderRead article