SMTP AUTH LOGIN Auth Handler.

NewMessage creates new mail message object with default From header.

NewMessageFrom creates new mail message object with custom From header.

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.