I've downloaded mailman from justasp.net. It's an ASP application that allows you to send an retrive Emails using the Jmail ver. 4,3 Component. For local email adresses on the server it is sending but when i use another server adresses i'm having the following error message. If anybody knows why, help me pls!

The message was undeliverable. All servers failed to receive the message
Unable to find codepage for charset:windows-1254
ClientLogging enabled: Client Remote Address: 213.14.32.106
.execute()
{
Trying server mail:mail.vedopromosyon.com
<- 220 X1 NT-ESMTP Server mail.vargonen.com (IMail 6.06 89296-7)
-> EHLO web01.vt.com.tr
<- 250-mail.vargonen.com says hello
250-SIZE 0
250-8BITMIME
250-DSN
250-ETRN
250-AUTH LOGIN CRAM-MD5
250-AUTH=LOGIN
250 EXPN
-> MAIL FROM:
<- 250 ok
-> RCPT TO:
<- 550 not local host yahoo.com, not a gateway
-> DATA
<- 503 must have sender and recipient first
Error: 503 must have sender and recipient first
Unable to find codepage for charset:windows-1254
ClientLogging enabled: Client Remote Address: 213.14.32.106
.execute()
{
Trying server mail:mail.vedopromosyon.com
<- 220 X1 NT-ESMTP Server mail.vargonen.com (IMail 6.06 89296-7)
-> EHLO web01.vt.com.tr
<- 250-mail.vargonen.com says hello
250-SIZE 0
250-8BITMIME
250-DSN
250-ETRN
250-AUTH LOGIN CRAM-MD5
250-AUTH=LOGIN
250 EXPN
-> MAIL FROM:
<- 250 ok
-> RCPT TO:
<- 550 not local host yahoo.com, not a gateway
-> DATA
<- 503 must have sender and recipient first
Error: 503 must have sender and recipient first