Deliverability
Nobody tells you when you cross it. No alert, no red banner — the replies just stop, and you spend the next month rewriting copy that was never the problem. You get one domain, you can spend all of it in an afternoon, and nobody sells you a second one.
So it is signed by you, from a domain you own. Sending from a free Gmail borrows a reputation that was never yours to build on, and every mailbox provider on earth already knows that trick.
About a minute, across your working hours. You would never send a hundred emails in six minutes. Nothing that reads your mail believes a person did either.
A new domain has no history, so it earns its volume instead of assuming it. The people who turn this off are the people who most needed it left on.
Addresses are checked before a word is spent on them, and a firm that bounces twice takes its whole domain out of the list. Bounces are what providers punish first, and fastest.
Checked the second before sending, not the day the draft was written. The person who opted out yesterday does not receive the email that was already in the queue.
Not us. Not anyone. "Delivered" only means a server took it. Where it went after that is never reported back to you. Every dashboard showing you an inbox-placement number is guessing, and most of them guess by tracking whether you opened it.
We do not track opens. Gmail loads the image before you do, Apple loads it whether you look or not, and the pixel is one of the things that gets mail filtered in the first place. It would damage the exact thing it pretends to measure.
You get the numbers that are real instead — bounces, complaints, replies, opt-outs — each one sitting next to the line where providers stop trusting you. Cross it and you hear about it that day, not six weeks later when the pipeline has gone quiet.