SMTP AUTH LOGIN Auth Handler.

NewContext initializes settings for mailer.

NewMessage creates new mail message object with default From header.

NewMessageFrom creates new mail message object with custom From header.

Send puts new message object into mail queue.

SendActivateAccountMail sends confirmation email.

SendCollaboratorMail sends mail notification to new collaborator.

SendIssueCommentMail composes and sends issue comment emails to target receivers.

SendIssueMentionMail composes and sends issue mention emails to target receivers.

SendRegisterNotifyMail triggers a notify e-mail by admin created a account.