SMTP Mail with ASP.net Error 5.5.1 Authentication Required

Question

Good day, I'm a beginner from using ASP.net and SMTP Mailer

Heres my Question, I always encounter this Error when i send email from my local and searched and tried the solutions around the net but not so lucky, I hope someone point out what codes do i need and where i encounter this errror

Message = "The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at"

Heres my Code:

protected void btnSendEmail_Click(object sender, EventArgs e)
        {
            // System.Web.Mail.SmtpMail.SmtpServer is obsolete in 2.0
            // System.Net.Mail.SmtpClient is the alternate class for this in 2.0
            SmtpClient smtpClient = new SmtpClient();
            MailMessage message = new MailMessage();

            try
            {
                MailAddress fromAddress = new MailAddress(txtEmail.Value, txtName.Value);
                smtpClient.Credentials = new System.Net.NetworkCredential("myUser@gmail", "password");
                // You can specify the host name or ipaddress of your server
                // Default in IIS will be localhost 
                smtpClient.Host = "smtp.gmail.com";
                smtpClient.EnableSsl = true;
                //Default port will be 25
                smtpClient.Port = 25;
                smtpClient.UseDefaultCredentials = false;
                //From address will be given as a MailAddress Object
                message.From = fromAddress;

                // To address collection of MailAddress
                message.To.Add("myEmail@gmail.com");
                message.Subject = txtSubject.Value;

                // CC and BCC optional
                // MailAddressCollection class is used to send the email to various users
                // You can specify Address as new MailAddress("admin1@yoursite.com")
                message.CC.Add("myEmail@gmail.com");

                // You can specify Address directly as string
                message.Bcc.Add(new MailAddress("myEmail@gmail.com"));

                //Body can be Html or text format
                //Specify true if it  is html message
                message.IsBodyHtml = false;

                // Message body content
                message.Body = txtaMessage.Value;
                message.BodyEncoding = System.Text.Encoding.UTF8;
                message.HeadersEncoding = System.Text.Encoding.UTF8;
                // Send SMTP mail
                smtpClient.Send(message);

                lblSuccess.Text = "Email successfully sent.";
            }
            catch (Exception ex)
            {
                lblSuccess.Text = "Send Email Failed.";
            }
        }

try to add `smtp.UserDefaultCreadential = true` and chage port to 587 — kulotskie, Aug 13 '15 at 05:10
@kulotskie tried that after reading this, still not working, same error shows — Enrique Gil, Aug 13 '15 at 05:14
@kulotskie `The SMTP server requires a secure connection or the client was not authenticated.` — Enrique Gil, Aug 13 '15 at 05:15

score 2 · Answer 1 · answered Aug 13 '15 at 06:12

i tried to make a simple codes for sending email try this

MailMessage mm = new MailMessage(); mm.From = new MailAddress("fromEmail"); mm.To.Add("toEmail"); mm.CC.Add("ccEmail"); mm.Subject = "StringSubject"; mm.Body = "BodySubject"; mm.IsBodyHtml = true; SmtpClient smtp = new SmtpClient(); smtp.Host = "smtp.gmail.com"; smtp.EnableSsl = true; System.Net.NetworkCredential NetworkCred = new System.Net.NetworkCredential(); NetworkCred.UserName = "UsernameString"; NetworkCred.Password = "PasswordString"; smtp.UseDefaultCredentials = true; smtp.Credentials = NetworkCred; smtp.Port = 587; try { smtp.Send(mm); } catch (Exception) { }

score 1 · Accepted Answer · answered Aug 13 '15 at 05:32

1

Try this reference ASP Simple SMTP for C# and VB it helps me a lot for may smtp problem

answered Aug 13 '15 at 05:32

kulotskie

331
1
16

didnt work, the approach must be too old to work on an Entity Framework 4.0 – Enrique Gil Aug 13 '15 at 05:45
Im using VS2015 and im using that code and its work 100% – kulotskie Aug 13 '15 at 05:47
baka sa email mo na mismong gamit yan kc sakin nag wowork naman sya ee – kulotskie Aug 13 '15 at 05:48
ASP kasi ung code ko eh, di ko alam kung same approach lang ba sila sa pagcall – Enrique Gil Aug 13 '15 at 05:50
sorry mali C# codes po yan ung ginamit na pang design is ASP and mark up lang po si asp more on design lang tlga – kulotskie Aug 13 '15 at 05:52
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/86849/discussion-between-enrique-gil-and-kulotskie). – Enrique Gil Aug 13 '15 at 05:58
di parin gumana still the same error parin ang lumabas `The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at` – Enrique Gil Aug 13 '15 at 06:01
http://chat.stackoverflow.com/rooms/86849/discussion-between-enrique-gil-and-kulotskie pasko ka bilis – kulotskie Aug 13 '15 at 06:03
paUP nalang din ng sagot ko aa salamat :3 – kulotskie Aug 13 '15 at 06:16

score 1 · Answer 3 · edited May 23 '17 at 12:25

1

Please have a look on google support team, what they are saying regarding sending mail from application. https://support.google.com/mail/answer/78775?hl=en

Also following link can help you.

Gmail Error :The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required

edited May 23 '17 at 12:25

Community

1
1

answered Aug 13 '15 at 06:11

Abid Hussain

102
1
10

@enrique Gil May gmail preventing you from sending email. – Abid Hussain Aug 13 '15 at 06:19
Thanks sir! Yes, I am prevented by Gmail because the Allow Less Secure Apps is not Turned on!! Thanks ! – Enrique Gil Aug 13 '15 at 06:40

score 1 · Answer 4 · answered Mar 03 '17 at 06:53

1

Goto Account of Gmail , then select Connected apps & sites Allow less secure apps: ON(if this is off you cannot send mails through apps,or your websites )

answered Mar 03 '17 at 06:53

SUDEEP

11
1

SMTP Mail with ASP.net Error 5.5.1 Authentication Required

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