Main Topics
Browse All TopicsWhen we try to send mail to a specific external address (EARTHLINK.NET), failure delivery report returned as below:
"SMTP Protocol Returned a Permanent Error 550 Authentication required."
We are using Domino 7.02 and Outlook as Pop3 client.
Any idea on this case? Thanks.
This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.
Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.
If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.
Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.
Access the answers to your technology questions today.
30-day free trial. Register in 60 seconds.
Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Try it out and discover for yourself.
30-day free trial. Register in 60 seconds.
Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.
For almost every mail server you need to authenticate to the mail server to send email externally. Otherwise the mail server(domino in this case) will see it as an attempt to relay off of it. Make sure you have the authentication settings configured correctly. You don't want to change the domino server to accept relays. Most mail servers will accept tls logins or plain text logins(base64).
Business Accounts
Answer for Membership
by: war1Posted on 2009-04-19 at 21:10:31ID: 24181838
Hello dickchan,
1. Check if outgoing mail server authentication is required. Select that option in account settings and use same settings as incoming server
2. Your ISP may be blocking port 25. Try using alternate port 587.
If no joy, you need to use your ISP SMTP server to send out emails.
Hope this helps!
war1