Zip Component, Email Component, Encryption Component ActiveX Control for Zip Compression .NET Components for ASP.NET
ActiveX and .NET Components for Zip Compression, Encryption, Email, XML, S/MIME, HTML Email, Character Encoding, Digital Certificates, FTP, and more ASP Email ActiveX Component

Index of Chilkat Blog Posts

November 16, 2007

550 5.7.1 Unable to relay

When sending email (SMTP), if you see this error it means that you need to provide SMTP authentication in order to send email outside your domain.

Make sure you’ve set both the mailman.SmtpUsername and SmtpPassword properties.

      550 5.7.1 Unable to relay for
      Failed when sending RCPT TO:<somebody123>

Does that mean that even if I use Windows Integrated Security I always have to provide a username and password as soon as I want to send a mail outside my domain?

Set both the SmtpUsername and SmtpPassword properties to "default", and Chilkat will use the current logged-on credentials (assuming your SMTP server supports NTLM authentication).

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