Notification delivery Error

Hi

I want to use notification delivery by gmail but it is someday that it dosen't work at all(from 29 march 2016) while it was working well up to this date .I used some other email provider such as yahoo that it worked well with those provider but it seems that gmail has done some restriction on your program or something like this .it is noted that I used this https://helpdesk.paessler.com/en/support/solutions/articles/76000041688-can-gmail-google-apps-be-used-for-smtp-relay but it was not useful and also turned on gmail "allow less secure app" button but it was not useful. it is useful to know that yahoo is not used because it banned rapid sending email as a suspicious activity. please check this matter at your side. my error in log is"Error sending "Email": Connection failed ("smtp.gmail.com")" all port is checked 25,465,587 with all four types of encryption (SSL v3, SSl v2, SSL v2 or SSL v3, TLS) without encryption but nothing happened