You can configure your G Suite instance to send mail using SocketLabs.
Please find the Instructions below, originally written by Google. We have included the links to Google's instructions for further reading.
Allow per-user outbound gateways
By default, users cannot use an outbound gateway. The G Suite mail servers deliver all outgoing mail, including mail that uses alternate From addresses.
To allow users to use an outbound gateway:
Sign in to your Google Admin console using an administrator account.
From the Admin console Home page, go to Apps > G Suite > Gmail > Advanced settings.
Tip: To see Advanced settings, scroll to the bottom of the Gmail page.
In the Allow per-user outbound gateways section, select Allow users to send mail through an external SMTP server when configuring a "from" address hosted outside your email domains.
At the bottom, click Save. Please note it can take up to an hour for changes to propagate to user accounts.
Once this option is enabled, users can configure their alternate email addresses to use an outbound gateway. Each user must configure this option individually.
Send emails from a different address or alias
- On your computer, open Gmail.
- In the top right, click Settings Settings and then Settings.
- Click the Accounts and import or Accounts tab.
- In the "Send mail as" section, click Add another email address.
- Enter your name and the address you want to send from.
- Click Next Step and then Send verification.
- For school or work accounts, enter the SMTP server (for example, smtp.gmail.com or smtp.yourschool.edu) and the username and password on that account.
- Click Add Account.
- Sign in to the account you added.
- Open the confirmation message you got from Gmail.
- Click the link.
- In the message, click the "From" line. (If you don't see this, click the space next to the recipient's email.)
- Select the address to send from.