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 Gmail Settings -> See All Settings -> Accounts and Import, and add an address in the Send mail as section. Be sure it's not marked as an alias.

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. In your android phone or tablet, open your Gmail app
   
   
2. At the top right, tap your profile picture
   
   
3. Tap Add another account
   
   
4. Choose the Other type of account to add
   
   
5. Enter the email address you're going to use with this SMTP Auth Service, and tap Next
   
   
6. Tap Personal IMAP
   
   
7. Enter your Inbound (IMAP) Server Password, and tap Next
   
   
8. Fill in the Username, Password, and Server fields.  The first two may already be filled in.
   Username: <Your Inbound (IMAP) Login
   Password: <Your Inbound (IMAP) Password
   Server: <Your Inbound (IMAP) Server
   
   Tap Next
   
   
9. Fill in the details for your Outgoing server:
   Require signin: Selected 
   Username: <Your Outbound (SMTP) Login
   Password: <Your Outbound (SMTP) Password
   Server: <Your Outbound (SMTP) Server
   
   Tap Next
   
   
10. Under Account Options, just tap Next
    
    
11. Enter your Account Name and tap Next and you're configured.
    
    
12. But let's make sure everything is secure.  
    1. On the top left, click the menu button next to Inbox
    2. Scroll down and click the Settings button
    3. Scroll down and find Incoming settings.  Click this link to view them.
       Port: <Your Inbound (IMAP) Server Port>
       Security Type: STARTTLS
    4. Scroll down and you'll see Outgoing settings. Click this link to view them
    5. Check the Port and Security type settings:
       Port: <Your Outbound (SMTP) Server Port>
       Security Type: STARTTLS
    6. Tap Done and you're - yes, you guessed it - done!