DKIM

DKIM (DomainKeys Identified Mail) adds a digital signature to your outgoing emails using a private key stored on your mail server. The corresponding public key is published as a DNS record. When a receiving server gets your email, it retrieves the public key from your DNS and uses it to verify the signature. If the signature matches, it confirms that the email hasn't been altered in transit and truly came from your domain. DKIM is essential for cold email because it directly affects deliverability. Emails without DKIM are much more likely to be flagged as spam. Most email providers (Google Workspace, Microsoft 365) automatically sign outgoing emails with DKIM, but you need to add the DKIM DNS records to your domain. To set up DKIM, generate a key pair through your email provider, add the public key as a DNS TXT record, and verify it's working with tools like MXToolbox or Mail-Tester.