When I send an email, I get error 505: “Client does not have permission to send as this sender; change the sender e-mail address”. How should I solve this?

This means that the SMTP server requires authentication before sending out an e-mail. Pass the login and password parameters in the Connect method. In VBScript, the code looks like this:

Set objSmtp = CreateObject( "AxEmail.Smtp" )
...
objSmtp.Connect( your.mailserver.com, user-id, password )