Sending bulk emails reliably requires upfront domain authentication, list hygiene, and a gradual warm-up plan. This topic covers the required preparation steps and best-practice recommendations to maximize deliverability and protect your sending reputation.
Preparations
Complete the following steps before you start sending bulk emails. Skipping any of these steps can reduce your email deliverability or cause your account to be suspended.
1. Set MX and SPF records
MX record: Improves deliverability. Some recipient mail servers check for an MX record before accepting messages. If you already have an MX record configured for receiving emails, you can remove the Direct Mail MX record.
SPF record: Prevents your sender address from being spoofed, stopping others from sending emails that impersonate your domain. Without an SPF record, spoofed messages can damage your sending reputation.
2. Set DKIM and DMARC records
These records are email anti-spoofing measures that increase your sending reputation and improve deliverability. Configure both before you send at scale.
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DKIM: In the Direct Mail console, find the configuration information for your email domain to get the record value. For more information, see What is DKIM? How do I set a DKIM record?
DomainKeys Identified Mail (DKIM) is an email security protocol that authenticates the sending domain using message signing. This verifies that an email was not modified in transit and ensures the integrity of the message body.
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DMARC: Configure this yourself without submitting a request. For more information, see What is DMARC? How do I set a DMARC record?
Domain-based Message Authentication, Reporting, and Conformance (DMARC) prevents others from spoofing your email domain and lets you receive reports about spoofing attempts. When a Mail Transfer Agent (MTA) that supports DMARC receives an email from your domain, it performs a DMARC check. If the check fails, a report is sent to the mailbox specified in your DMARC settings.
3. Provide a valid unsubscribe link
Every email must include a unique unsubscribe link containing the recipient's email address. When a recipient clicks the link, your unsubscribe service receives the request. Parse the recipient's address from the request and remove it from your recipient list. You are responsible for implementing and maintaining this unsubscribe process.
4. Test your emails before sending
Use mail-tester.com to check email quality before you send at scale. Send a test email to the temporary mailbox generated on the page to see whether it is marked as spam. Note that this is a third-party service — avoid including sensitive information in your test content. Results are for reference only, as each email provider uses a different anti-spam system.
5. Add your sender address to your company's allowlist
If you are sending emails to recipients within your own organization, ask your email administrator to add your sender address to the allowlist. This prevents your messages from being filtered before they reach internal recipients.
6. Notify recipient email providers in advance
If you send newsletters or notifications to your members, contact their email service providers before you start sending. This is especially important when sending to large lists for the first time.
Suggestions for sending emails
Warm up your email domain
A sudden burst of high-frequency sending can trigger throttling by recipient servers. Warm up your email domain by gradually increasing your sending volume. Spread your sends evenly across each day rather than batching them. For a detailed schedule, see Warm-up guide.
Maintain a high-quality recipient list
Send only to users who have explicitly consented to receive your emails. Remove invalid addresses promptly. A high bounce rate or spam complaint rate triggers system rules that lower your sending reputation or result in account suspension.
Avoid repetitive sending patterns
Do not send emails with the same subject line to many recipients at the same email service provider in a short period. This pattern is a strong spam signal and causes your messages to be filtered automatically.