For information on how to setup a Mailgun account, see article "Mailgun Setup".
If you are transferring your domain into Cloudflare from another DNS provider, please do so before continuing with this article.
Step 1: Retrieve MX and TXT records from Mailgun
Log into your account in Mailgun and add a domain from the top menu bar. Once your domain is added, you will see that Mailgun gives you a few MX records and TXT records to be added for your domain, for both successful email forwarding and verification of the domain.
Step 2: Add MX and TXT records into Cloudflare
Choose your site and select DNS Settings
Add the CNAME record. Name = email, Value = mailgun.org, TTL = Automatic (these are examples, please use the actual items from your account)
IMPORTANT: Make sure the Cloudflare cloud is gray and not orange/active => You have to click on the cloud icon to change this to DNS only
Add the two MX records (these are examples, please use the actual items from your account)
Name = domain.com (no www), value = mxa.mailgun.org, Priority = 10
Name = domain.com (no www), value = mxb.mailgun.org Priority = 10
Add the two TXT records (these are examples, please use the actual items from your account)
Name= domain.com (no www), value = v=spf1…
Name = smtp._domainkey, value = k=rsa…
Step 3: Add your mail routes in Mailgun
Log into your Mailgun account and go to Routes section from the top menu. Now add as many routes as you want.
For example, if your domain is example.com and you want the mail sent to hello@example.com to be forwarded to doctor@who.com, then that would be a route.