What makes a good sending domain
It should be obviously yours. A prospect who looks at the address should see your brand, not a random string. Prefix patterns (try-, get-, hello-) and suffix patterns (-hq, -team) both work. Avoid anything that could be read as impersonating another company, and avoid hyphen-heavy names on .biz or .info, which are heavily filtered.
How many to buy
Use the volume planner. At 40 emails per inbox and 3 inboxes per domain, each domain carries about 120 cold emails a day. Buy them on the same registrar, set them to forward to the main site, and give each one MX records so replies work.
Questions
Should cold email domains be .com?
.com is safest. .co and .io are fine for tech audiences. Avoid .biz, .info, .xyz and other endings with a spam reputation.
Should sending domains redirect to the main site?
Yes. A visitor who types the domain into a browser should land on your real site. It is also what receivers expect from a legitimate sender.
