Error while sending an email form my website with SmtpClient.

Posted on 2009-05-14
Last Modified: 2013-12-17
I'm developing a website with ASP.NET 2005 and C#. I tried to send emails from my website
using the code I put in code section.
it gives me the follwing error:
"Bad sequence of commands. The server response was: This mail server requires authentication when attempting to send to a non-local e-mail address. Please check your mail client settings or contact your administrator to verify that the domain or address is defined for this server"
If I change the mairTo to ""  which is my website, it'll work fine. But this way I can only send emails to my own website.!
Please help me how to solve my problem.
string mailFrom =  "";
 string mailTo =      "";;
        System.Net.Mail.MailMessage email = new System.Net.Mail.MailMessage("", mailTo);
        email.Subject = "subject";
        email.IsBodyHtml = true;
        email.Body = " body of the email";
        System.Net.Mail.SmtpClient mailClient = new System.Net.Mail.SmtpClient();
        System.Net.NetworkCredential basicAuthenticationInfo = new System.Net.NetworkCredential("", "my_password", "");
        //mailClient.Host = "";
        mailClient.Port = 25;
        mailClient.UseDefaultCredentials = false;
        mailClient.Credentials = basicAuthenticationInfo;
        catch (Exception ex)
           return ex.string();

Open in new window

Question by:Elham_Seif
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 70

Assisted Solution

by:Éric Moreau
Éric Moreau earned 100 total points
ID: 24384174
you will surely find your solution from

Assisted Solution

by:Faheem Shaikh
Faheem Shaikh earned 100 total points
ID: 24384430
Have a look here for some causes and resolutions of this:

Accepted Solution

Ramone_Hamilton earned 300 total points
ID: 24384612
Are you using your own smtp server?  If so check to make sure that it is capable of sending e-mails outside of your domain.  I believe that most webmails such as hotmail, yahoo or gmail won't accept your e-mails unless they are coming from a legit exchange or smtp server connected to a static ip address.
The Eight Noble Truths of Backup and Recovery

How can IT departments tackle the challenges of a Big Data world? This white paper provides a roadmap to success and helps companies ensure that all their data is safe and secure, no matter if it resides on-premise with physical or virtual machines or in the cloud.


Author Comment

ID: 24385627
I got confused reading those long sites about emails.
Would you please read my code and tell me what's wrong with the code?
What can I use instead, to make it run correctly.
The one that can correct my code will get the points.
Thanks in advance.

Expert Comment

ID: 24385753
You haven't set the address of the smtpclient you are sending from.  Try this:

System.Net.Mail.SmtpClient mailClient = new System.Net.Mail.SmtpClient("");

Author Comment

ID: 24386458
Hi Ramone_Hamilton
my host is
what should I write instead of "" in the code you said?

Expert Comment

ID: 24386804
Are you running your own smtp service or is your web page being hosted by another company?

Author Comment

ID: 24401179
Hi Ramone_Hamilton
My website is hosted by another company.
How can I run my won smtp service? And what's the diffrence?

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Resolve Outlook connectivity issues after moving mailbox to new Exchange 2016 server
As tax season makes its return, so does the increase in cyber crime and tax refund phishing that comes with it
In this video we show how to create an Address List in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Organization >> Ad…
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…

717 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question