An application which uses the SocketTools SMTP client component to submit e-mail messages for delivery fails with error 0x8004274C (10060) or error 0x8004274D (10061). This indicates that the connection has timed out, or was refused by the remote host.
By default, port 25 is used to submit e-mail messages for delivery to an SMTP server. However, port 25 is widely abused by malware and spyware and is commonly blocked by Internet service providers unless the connection is made to their own mail servers.
To resolve this issue, port 587 can typically be used as an alternative port number. It is important to note that using port 587 usually requires the client to authenticate, otherwise the message submission will be rejected. If you cannot connect using either port 25 or 587, contact the system administrator for the mail server to determine if there's an alternate port number that you can use.
To authenticate the client session using the .NET class or ActiveX control, set the Extended property to true, set the UserName and Password properties to the appropriate values and call the Authenticate method. To authenticate the client session using the library API, specify the option SMTP_OPTION_EXTENDED when calling the SmtpConnect function and then call the SmtpAuthenticate function after the connection has been established.