You can configure the email server from the Payara UI (see my other answer on how to get access to it What is the default user name and password of Payara server?)
In Payara you’ll find a resource called
mail/BBCMail (You’ll find it under
Resources > JavaMail Sessions). From there you’ll be able to configure your email provider.
Please note that if you want to use Gmail as email provider you need to configure Gmail to allow “unsecure apps” (see here: https://support.google.com/accounts/answer/6010255?hl=en).
Once the configuration is done, ssh into your machine and restart the web server
systemctl restart glassfish-domain1.
After this, if everything is configured correctly, you should be able to receive the verification emails.
Additionally, if you have access to the admin account, you are not strictly required to have configured an email server to enable other users. As admin you can overrule the verification process. See this documentation page (https://hopsworks.readthedocs.io/en/latest/admin_guide/user-administration.html#activating-users-without-a-mail-server)