KBA-3399 says:
The GmailSMTP server settings for sending mail through Gmail from any email program are:
• Gmail SMTP serveraddress:smtp.gmail.com
• Gmail SMTP user name: Your full Gmail address (e.g.
example@gmail.com)
• Gmail SMTP password: Your Gmail password
• Gmail SMTP port (TLS): 587
• Gmail SMTP TLS/SSL required: yes
...and does your ISP permit SMTP and TLS protocol/port 587?
Here are the settings that worked within the ZD Configure / System section:
[ User-added image ]
There are times when one has 2-step security verification enabled in your gmail account. The above parameters will not work if one has 2-step verification security enabled. To make it work, disable 2 step verification or go to the Account settings option of your gmail. Within the Account options, select Security. Within Security, select the 2-step verification settings. Then log in and select the App Specific Passwords section tab. Then click on the Manage 'Application-specific passwords' tab. There the SW will generate a password for you to use in the SMTP Authentication password section.