[JAY]

How to Set Up an SMTP Relay in BillionMail (Amazon SES, Brevo, Mailgun)

By default BillionMail delivers email straight from your server to Gmail, Outlook and the rest. That's the whole point of running your own mail server. But sometimes it's better to send through an SMTP relay: an outside email service that delivers the mail for you.

When a relay makes sense

• Your provider blocks outgoing port 25 and won't unblock it. See how to check if port 25 is blocked.
  
• Your server's IP is new or has a poor reputation, and you need mail to arrive today while you warm it up. See the IP warm-up plan.
  
• Your IP is on a blacklist and delisting takes time.
  

With a relay, BillionMail still handles your contacts, templates, campaigns and stats. Only the last step, the actual delivery, goes through the relay.

Which relay?
BillionMail has presets for Gmail, Mailgun, AWS SES and SendGrid, plus Custom SMTP for anything else (Brevo, Postmark, SMTP2GO and others). Amazon SES is usually the cheapest for volume; Brevo and Mailgun are easier to start with. Avoid using a personal Gmail account for newsletters: it has low daily limits and it's against Google's rules for bulk mail.

Step 1: Set up the relay service
Every service works roughly the same way:

1. Create an account.
   
2. Verify your domain. The service gives you DNS records to add (usually DKIM CNAME or TXT records, sometimes a return-path CNAME).
   
3. Create SMTP credentials. These are not your login password. In Amazon SES it's under SMTP settings > Create SMTP credentials; in Brevo it's SMTP & API > SMTP.
   
4. For Amazon SES: new accounts start in the sandbox and can only send to verified addresses. Request production access before going live.
   

Step 2: Add the relay in BillionMail
Open SMTP in the left menu and click Add. Choosing Amazon SES fills in the server and port for you:


Fill in:

• Remark: a name for this relay.
  
• Bound Domain: which of your sending domains should use this relay. Domains not bound keep sending directly.
  
• SMTP Server and SMTP Port: for SES, BillionMail fills in
  Code:Copy

  email-smtp.us-east-1.amazonaws.com
  and 587; change
  Code:Copy

  us-east-1
  to your SES region if it's different. For Brevo,
  Code:Copy

  smtp-relay.brevo.com
  and 587. For Mailgun,
  Code:Copy

  smtp.mailgun.org
  (or
  Code:Copy

  smtp.eu.mailgun.org
  for EU accounts) and 587.
  
• Username and Password: the SMTP credentials from Step 1.
  

Click Test Connection. If it passes, save.

Watch out for browser autofill: your browser may fill the BillionMail admin login into the Username and Password fields. Clear them and paste the relay's credentials.

Step 3: Fix SPF and DKIM
This is the step people forget. Your SPF record must allow the relay to send for your domain, for example:

Code:Copy

v=spf1 mx a include:amazonses.com ~all

Each service documents its own include. Only one SPF record per domain: add the include to the record you have, don't create a second one. Also make sure the relay's DKIM records from Step 1 are green in the service's dashboard. With SES, setting up a custom MAIL FROM domain makes SPF align with your domain for DMARC. Background in BillionMail DNS setup explained.

Step 4: Test
Send a test from a campaign or the Send API, then open the email in Gmail and choose Show original. You want SPF: PASS, DKIM: PASS and DMARC: PASS. If the email is stuck, the delay reason in Settings > Send Queue tells you why; see emails stuck in the send queue.

Common errors

• Authentication failed: wrong SMTP credentials, or (SES) the credentials were made in a different region than the server name.
  
• "Email address is not verified" (SES): you're still in the sandbox, or the From domain isn't verified.
  
• Connection timed out: try port 465 or 2525 if the service offers it.
  

More BillionMail guides

• Send API for transactional email
  
• WordPress email through BillionMail SMTP
  
• Import contacts, groups and tags
  
• Email templates explained
  
• Mailboxes and webmail
  
• Campaign analytics explained
  
• IP warm-up plan
  
• Move from Mailchimp or Sendy
  
• Add a second sending domain
  
• Send your first newsletter · DNS setup explained · Deliverability testing
  

Applies to BillionMail 4.9, October 2026. Replace

Code:Copy

example.com

and

Code:Copy

mail.example.com

with your own domain and mail hostname. Menu names can change a little between versions.