Send email Exception

[snir c]

Hello

I configured Outgoing Mail and when I clicked on "Test connection" I got 

"The connection was successful."

but when I try to Send a Test Email 

It returns to the log 

An error has occurred with sending the test email:
com.atlassian.mail.MailException: com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first. o16-v6sm6705238wmf.10 - gsmtp 

[snir c]

I tried Yahoo Mail smtp.mail.yahoo.com 

and when I Send a Test Email I'm getting this:

An error has occurred with sending the test email:
com.atlassian.mail.MailException: com.sun.mail.smtp.SMTPSendFailedException: 450 Requested mail action not taken: mailbox unavailable

at com.atlassian.mail.server.impl.SMTPMailServerImpl.sendWithMessageId(SMTPMailServerImpl.java:225)
 at com.atlassian.mail.server.impl.SMTPMailServerImpl.send(SMTPMailServerImpl.java:162)
 at com.atlassian.jira.plugins.mail.webwork.SendTestMail.doExecute(SendTestMail.java:107)

[Moses Thomas]

@snir c  Sorry  that  you  are facing this  issue but it looks like you  have tumbled into  the issue below, please try  resolution  here  Unable to Send Email Due To SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first

Best!

[snir c]

It wasn't helped me 

I'm using Gmail SMTP server