Mandrill (Mailchimp Transactional)

Mailchimp Transactional (Mandrill)

Mailchimp's paid transactional email add-on. Requires an active Mailchimp account with the Transactional add-on enabled.

Easy~5 minAPIPaid only

Mandrill is paid-only

Unlike most providers in this list, Mandrill has no free tier. You need a paid Mailchimp Standard / Premium plan plus the Transactional Email add-on (~$20/month minimum).

Prerequisites

• An active Mailchimp account with the Transactional Email (Mandrill) add-on enabled.
• A verified domain in Mandrill.

Step-by-step

Enable Transactional in Mailchimp

Sign into Mailchimp → click your account icon → Transactional. If it says "Get started", you'll need to add it as a paid add-on first.

Verify your sending domain

Mandrill dashboard → Settings → Domains → Sending Domains → Add Domain. Enter your domain.

Mandrill shows DNS records (DKIM, SPF, custom return-path). Add them at your DNS provider, then click Test DNS Settings to verify.

Generate an API key

Mandrill → Settings → API Keys → + Add API Key. Name it "SendGrail" and create.

Copy the API key.

Add the connection in SendGrail

WordPress admin → SendGrail → Connections → Add Connection → pick Mandrill.

Fill in:

• Connection Name: Mandrill
• From Email: an address on your verified domain
• From Name: display name
• API Key: paste from step 3

Click Save.

Test

SendGrail → Test Email → pick Mandrill → send.

Troubleshooting

Invalid_Key

API key is wrong or revoked. Generate a new one in Mandrill → Settings → API Keys.

Unsigned

Sending from a domain Mandrill hasn't signed. Make sure your domain shows Verified + DKIM Valid in Settings → Sending Domains.

Reject reason: spam

Mandrill's reputation system flagged the email. Check your sender reputation in Reports → Reputation. May indicate compromised credentials or low-quality recipient lists.

What's next

• Email Routing — route specific email types through Mandrill while others go to free providers.
• Failure Alerts — get pinged if Mandrill bounces.