TL;DR (Too Long, Didn't Read)

Gather the info from our Control Panel by clicking the SMTP Auth Relay tab on the left menu.  You'll have to click the eye icon to view your passwords.  If you don't have a local password set up, you'll be asked to create one.  The Inbound (IMAP) and Outbound (SMTP) servers may have different logins and will have different passwords.   Go into your Mail app and add a new account email account using this info.

When you send email, click the From address to choose your new account for sending email.  It'll pass SPF, DKIM, DMARC checks.  Congratulations!

Long Version

Gather the info you need to configure your email client

To configure your email client to use the MailRoute SMTP Auth Relay service for outbound email relay, you will need to gather some info from the MailRoute Control Panel and then configure your email client. 

1. Login to admin.mailroute.net and click the My Settings link at the top of the page.
   
   
2. Click the SMTP Auth Relay tab in the Settings menu on the left side of the page. 
   
   
   
   
3. Gather your info!  You can click the copy icon  to copy the values of any field.
   
   For the Gmail webmail interface, you will only need the info in the Outbound (SMTP) Server configuration.
   
   
   Outbound (SMTP) Server Password:  Click the eye icon to display your password. Accept the Terms of Service:
   
            
   
   By the way, you can generate a new password for your Outbound (SMTP) Server at any time.

Configure your email client

1. Launch the Outlook application.
   
   
2. Click the Settings icon in the top menu bar of the application.
   
   
3. Select Accounts from the left hand menu and then then click +Add account.
   
   
4. Enter your email account in the Suggested Accounts field and press Continue.
   
   
5. In the Select your email provider window, scroll down and click on IMAP.
   
   
6. Enter the following information in the IMAP window:
   
   Password: <Your Inbound (IMAP) password>
   
   IMAP Incoming server: <Your Inbound (IMAP) Server>
   
   Port: 993  (Please note this is different than in the MailRoute Control Panel) - Outlook only supports using this port and SSL/TLS encryption)
   
   Secure connection type: SSL/TLS (Recommended)
   
   SMTP username:  <Your Outbound (SMTP) Login>
   
   SMTP password: <Your Outbound (SMTP) Password>
   
   Port: 587
   
   Secure connection type: SSL/TLS (Recommended)
   
   Then click Continue.
   
   
7. In the Sync your IMAP account window, click Continue.  You should see a Success windows congratulating you for your hard work.

Using your new account to send email

When you compose a new email, you'll have a menu where the From address is displayed.  Click it and choose your new account from the popup menu.