You can use a gmail account to test the XSOAR mail listener and run phishing excursuses. You will need to set insecure apps in the gmail account.
The security settings are located on the left hand menu.
The insecure apps feature can then be turned on to enable testing. This should only be done with a testing account!
The integration settings are then as follows
Mail server hostname: imap.gmail.com
IMAP Port: 993
Use TLS for connection
Don't verify certificate
Hostname: smtp.gmail.com
Port: 587
Don't verify certificate
STARTTLS for connection type