The two most probable reasons are:
1. Your e-mail client is not configured to authenticate itself before before sending through the SMTP server. For security reasons, our servers require you to check your email before sending any messages. Please make sure that you have SMTP Authentication enabled in your email client and visit the guidelines for configuring Outlook.2. Your ISP blocks port 25.
In case your ISP is filtering the default SMTP email port 25, you can use an alternative 26 port, which we have opened for you. In your email client configuration you should choose 26 as a default SMTP port and you will be able to send your messages
Â Many major ISPs are blocking outgoing emails. The reason they do this is to prevent you from using their internet connection for spamming purposes. You will still be able to send emails, but only by using your ISP'S outgoing mail server. Every ISP's outgoing mail address is different, but for the most part they will be mail.yourispname.com.
Common Local SMTP Servers are:
Internet Solutions : smtp.isdsl.net
SAIX: smtp.saix.net or smtp.telkomsa.net
MWeb - smtp.mweb.co.za
@lantic - smtp.lantic.net
IBurst - smtp.wbs.co.za
Vodacom GRPS/3G - smtp.vodacom.co.za
MTN Edge/GRPS/3G - smtp.mtn.co.za