Nexus220 uses SSL security protocol for email notifications. Most email servers require TLS security protocol.
SMTP2GO will allow SSL security connections.

Go to https://app.smtp2go.com/, Select create free account.

Select the Free Plan, Enter a Name and Create a Password

use an email address for the account,

Confirm your email address and Activate your account.

After you Select Activate Account,

The SMTP 2 Go website will open. You will need to add a Verified Sender.

Select Add a Verified Sender

Select Add a Single User

Add your own email address and select Send verification Email.

Once the Sender Email is Verified, Create an SMTP Username

Go to Sending/SMTP Users and select continue

Select Add SMTP User

Create a Username and Password for the SMTP User.

This username and password will be used in Nexus220.

In the Nexus220 Configuration Page, Enter the Information

Select Add a Single User

The SMTP to go set up is complete