Gmail: 530 5.5.1 Authentication Required. Learn mo

Question

This Go program successfully sends email from my home computer, but on a virtual server on DigitalOcean receives the following error:

panic: 530 5.5.1 Authentication Required. Learn more at

Here's the code:

auth := smtp.PlainAuth("", "[e-mail]", "PASSWORD", "smtp.gmail.com")
msg := "Subject: Hello\r\n\r\nWorld!"
e = smtp.SendMail("smtp.gmail.com:587", auth, "[e-mail]", []string{email}, []byte(msg))
if e != nil { panic(e) }

Answer 1

Derp! I signed into the account and there was a "Suspicious login attempt" warning message at the top of the page. After clicking the warning and authorizing the access, everything works.

Answer 2

Get to your Gmail account's security settings and set permissions for "Less secure apps" to Enabled. Worked for me.

Answer 3

You need to go here https://security.google.com/settings/security/apppasswords

then select Gmail and then select device. then click on Generate. Simply Copy & Paste password which is generated by Google.

Answer 4

You need turn on the POP mail and IMAP mail feature in setting of the email you are using to send mail. Good luck!