It probably has something to do with the SMTP server. Not all SMTP server allows simple "HELO" exchange with the email client like TLServer. You probably need to use TELNET and manually handshake with the SMTP server to find out why it doesn't work. This is beyond the normal support of the PLC topics so you probably need to consult tech expert on SMTP system. But I can give you some instruction as follow but I can't support you further than that:
you have to telnet to your smtp server from your computer in order to open the port. So lets do it one step at a time:
1) Click "Start" then "Run", then enter the following line into the "Open" text box:
telnet smtp.wanadoo.co.uk 25
2) A console should open and it will attempt to connect to port 25 of smtp.wanadoo.co.uk If successful there will be some messages annoucing that it is an email server such as SENDMAIL.
3) Next, you have to enter the following:
HELO yourname@yourdomain.com
If it says "501 5.0.0 Invalid domain name", then try the following:
HELO yourdomain.com
4) If successful, it will say "....pleased to meet you". Then type the following:
MAIL FROM: yourname@yourdomain.com
5) It should say "Sender OK". Then enter the following:
RCPT TO: recipientname@recipientdomain.com
6) Next, enter
DATA and press <ENTER>
7) Now you can type in multiple lines of contents for the message body. When end, type a single "." on the beginning of the line and press <Enter> to end the message. The recipient should then receive an email if all is well.
If you are unable to proceed further then your smtp server is not cooperating and may require more sophiscated login method. In that case you may have to use a different SMTP server.