SparkPost & Mailtrap

Warning

Always use subaccounts in Sparkpost! Otherwise there may be compliance issues which can lead to the closing down of the whole Renuo account.

Introduction

Main (Sparkpost, [email protected])

• Each app is using a separate subaccount under the main account
• The Domain should be set up and verified under the subaccount’s sending domains
• Login: [email protected]

Develop (Sparkpost, renuoapp.ch)

• Each app is using a separate subaccount under the main account

• The emails will be sent with *@renuoapp.ch as your mail sender

• Login: [email protected]

• If you want, you can also use Mailtrap for develop. Create a new Inbox https://mailtrap.io/inboxes and use this credentials

Testing (Mailtrap)

• Login: [email protected]
• The Email will be caught by Mailtrap and not forwarded to the intended receiver
• You can login to Mailtrap to see the sent email

Sparkpost

Warning

Always use subaccounts for the project, so that the whole account doesn’t get suspended / blocked in case of compliance issues!

1. Go to https://app.sparkpost.com/auth and log in with the credentials for sparkpost+enviroment@renuo.ch found in the credential store
2. Create one new subaccount and name it like your project
3. Create a new API-Key for your subaccount and assign it to the new subaccount, with the following permissions: Send via SMTP, Sending Domains: Read/Write
4. Write down the API-key in the credential store (in a list under sparkpost+enviroment@renuo.ch), because it’s only showed once!
5. Credentials for SMTP setup on your app can be found here, password is your generated API-key
6. (if domain is known) Add your sending domain here. Assign it to the subaccount. Set up SPF, DKIM and DMARC with TXT DNS records (only use renuoapp.ch within the [email protected])
7. Verify your Email DNS configuration with https://mxtoolbox.com/SuperTool.aspx
8. Set up your ENV-variables and test if the mails are working. Manual test emails can be send via the following command in the rails console (production environment): ActionMailer::Base.new.mail(to: '[email protected]', from: ENV['MAIL_SENDER'], subject: 'Testmail', body: 'Mail content').deliver!
9. Send a test email to https://www.mail-tester.com/ or https://www.experte.com/spam-checker and check the result

For DNS setup also see Go Live

ENV-variables example:

MAIL_USERNAME: 'SMTP_Injection'
MAIL_PASSWORD:  'YOUR API KEY'
MAIL_HOST: 'smtp.sparkpostmail.com'
MAIL_SENDER: 'Sample App <[email protected]>'

Or with a custom domain:

MAIL_SENDER: 'Sample App <[email protected]>'

Mailtrap

ENV-variables example:

MAIL_USERNAME: 'found in credential store'
MAIL_PASSWORD:  'found in credential store'
MAIL_HOST: 'smtp.mailtrap.io'
MAIL_SENDER: 'Sample App <[email protected]>'

Set up your ENV-variables and test if the mails are working. Manual test emails can be send via the following command in the rails console (production environment): ActionMailer::Base.mail(to: '[email protected]', from: ENV['MAIL_SENDER'], subject: 'Testmail', body: 'Mail content').deliver_now!

Bounce Domain

What is a bounce domain?

A bounce domain (also called a Return-Path domain, MAIL FROM domain, or envelope-from domain) is the domain designated to collect undeliverable message notifications (bounces). It is normally visible in the email’s Return-Path header.

From:           [email protected]
Return-Path:    [email protected]

From: Shows the sender to the recipient.

Return-Path: Tells the receiving mail server where it should send the bounces.

When an email can’t be delivered, the receiving mail server sends a bounce to the envelope sender.

How it works

1. Your application sends an email through SparkPost.
2. The recipient’s mail server tries to deliver the email.
3. If delivery fails, the mail server sends a bounce to the envelope sender (Return-Path).
4. The Return-Path uses your bounce domain.
5. SparkPost receives the bounce and records the delivery failure.

Why is a bounce domain needed?

Bounce domains are useful for automated or high-volume email sending, such as newsletters or notifications. Some emails will fail to be delivered because the recipient does not exist or their mailbox is full etc. The receiving mail server sends these bounces to the Return-Path.

For further information visit here

Configuration

For a normal SparkPost setup, use a subdomain for the bounce domain:

Sending domain:     mail.renuo.ch
Bounce domain:      bounce.renuo.ch

Do not use the root domain if it is also used for normal incoming email. Using a dedicated subdomain avoids interfering with your existing email configuration.

DNS records

SparkPost will provide a CNAME record that you need to add to your DNS provider.

Verify bounce domain

1. In the domains tab, select Bounce Domains
2. Click “Add Bounce Domain”
3. Enter a subdomain instead of your root domain, click “Save and Continue”

Warning

Use a dedicated subdomain for the bounce domain. Bounce domains are used to collect undeliverable message notifications. Using a subdomain avoids interfering with the root domain’s existing mail configuration.

4. Add the record name and value to your DNS provider
5. Select type CNAME and turn off the proxy. This prevents traffic from diverting to Cloudflare instead of the mail server
6. Click “save”
7. Go to the DNS page on SparkPost and click “Verify Domain”.

DNS authentication

SPF

Sender Policy Framework proves that an authorized server is allowed to send emails for your domain. In other words, it says “This email came from a server my domain authorized to send mail.”

DKIM

DomainKey Identified Mail allows owners to automatically sign emails from their domain. This proves the mail really came from the domain.

DMARC

Domain-based Message Authentication Reporting and Conformance tells the receiving mail server what to do after checking SPF and DKIM. For example marking the email as “spam”, deliver it anyway or dropping it entirely.