To help keep deliverability as high as possible, Mandrill requires that every sending domain is configured to allow Mandrill to send authenticated emails on behalf of that domain.
You'll need to add SPF and DKIM records and verify ownership of your sending domains before you can send email through your account. Mandrill will not send any email from unverified domains or domains without valid SPF and DKIM records, including public domains like gmail.com, yahoo.com, and more.
A message that is rejected with the reject reason unsigned indicates that the sending domain hasn't been properly set up, and that your account is unable to send and authenticate email from that domain.
Add a New Sending Domain
- Go to Settings.
- Choose Sending Domains.
- Type a new domain at the top and click Add.
You can also add sending domains via the Mandrill API.
Add DNS Records and Test Sending Domain Settings
Now that you've added a new sending domain, add the appropriate records to your domain's DNS settings.
After you've added the correct records, click the Test DNS Settings button to check the DNS settings for your sending domain.
When the test is done, click the View DKIM Settings and View SPF Settings links for more information about your current settings and any suggested changes.
You can also check sending domains via the Mandrill API.
Verify the Domain
Domain Verification is required to configure a sending domain. Verification used to be optional for many Mandrill users, so please check that any domains actively used for sending have three green check marks on the sending domains page:
Verify a domain on the Sending Domains page in your Mandrill account or with the Mandrill API using the /senders/verify-domain endpoint. To confirm ownership of the domain, we'll send an email with a confirmation link to the address you specify, so you'll need to make sure that the domain can accept incoming email.