Mid-week mornings are marginally better than Friday afternoons. That is about the whole of it, and it is worth doing because it costs nothing.
Budget cycles matter more. A message that arrives while the money for next year is being decided is a different message from the same one in month two of a locked budget.
Anyone claiming a specific minute is selling certainty they do not have.
How many cold emails a day can one mailbox send?
Fifty, with warm-up counted inside that number. The ceiling is not technical: Google Workspace allows 2,000 messages a day per account, far more than a cold mailbox should ever send. The limit that matters is reputation, and the reply data agrees. In Hunter's 2025 data, accounts sending 20 to 49 emails a day reached a 5.7% reply rate, against a 4.5% average.
| Daily emails per account | Reply rate |
|---|---|
| 20 to 49 | 5.7% |
| All accounts, average | 4.5% |
Why add mailboxes instead of sending more from each?
Because the complaint budget is small. Google asks senders to keep the spam rate in Postmaster Tools below 0.10% and never to reach 0.30%. At 0.10% that is one complaint per thousand emails. Many domains each sending a little keep one bad day on one domain from becoming everyone's problem.
Sources: Hunter, The State of Cold Email, 31 million emails sent by Hunter users in 2025; Google, Email sender guidelines; Google Workspace, Gmail sending limits.
Sending runs on working days, spread across the pack, at no more than fifty a day per mailbox. The rhythm is set by the infrastructure, not by a theory about Tuesdays.