Email Error Message

Could someone explain why I’m getting this error message when attempting to email an invoice.
Cheers
Mike

System.Net.Mail.SmtpException: System.Net.Mail.SmtpException: Syntax error, command unrecognized. The server response was: 5.7.0 Mailgun is not loving your login or password
at System.Net.Mail.RecipientCommand.CheckResponse(SmtpStatusCode statusCode, String response)
at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, Boolean allowUnicode, SmtpFailedRecipientException& exception)
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at ManagerServer.HttpHandlers.Businesses.Business.Email.Post()

Read this Guide: https://www.manager.io/guides/10643.

In the future, check the Guides as your first resource. Then search for previous forum topics. This has been discussed already many times in the past week.

Thanks,
All sorted but took a while to get the settings required.