Cold Email Warm-Up and Deliverability Guide

Authenticate first

Before sending a single email, publish SPF, DKIM and DMARC records for the domain. Without them, receivers cannot tell your mail from a forgery. The custom email domain page explains each record.

Warm up gradually

• Start with a small number of emails a day to people who will open and reply.
• Increase steadily over weeks, not days.
• Keep sending every day, rather than in bursts.
• Pause the increase when bounces or complaints rise.

Watch reputation

• Bounce rate: remove invalid addresses at once.
• Spam complaints: keep these as close to zero as you can.
• Replies: real replies are the strongest positive signal.
• Use the free reputation dashboards your mailbox providers offer, such as Google Postmaster Tools, for your domain.

Write email that earns the inbox

• Send to people who have a reason to hear from you.
• Keep it short and plain, with one clear ask.
• Avoid heavy images, URL shorteners and all-capital subject lines.
• Include a simple way to opt out and honour it.

Separate cold outreach from customer mail

Use a different sending domain or subdomain for cold outreach than for invoices and customer messages. If outreach damages its reputation, your important mail is unaffected.