If you use the Email Collector to collect from GMAIL and select Social Authentication Type to collect items from a user with a known password you will get the error "Unexpected server response: 'IMAP002 NO [ALERT] Please log in via your web browser: https://support.google.com/mail/accounts/answer/78754 (Failure)'" upon collection.
The GMAIL account has "Allow less secure apps" disabled.
In the GMAIL account you wish to collect from you should ensure to enable "Allow less secure apps".
In the event 'allow less secure' does not enable collection from Gmail and you are still denied, in the my account section of the gmail account. Look for Device Activity and Notifications. There is a recent securty events section , here you can see the denied attempt and you will be granted the option to allow connections from that location.
3.7; 3.7 Service Pack 1; 3.7 Service Pack 2