Outlook SMTPClient server error 5.3.4 5.2.0

I have an MVC .NET web application that has been running stable for the most part of a year now. However today we received an error code and I'm having trouble finding how to resolve the issue.

In the application, I use SMTPClient to send emails out. For this, we use an Outlook email account. This was working fine until today. The error code that I get is this:

Mailbox unavailable. The server response was: 5.3.4 554-554 5.2.0 STOREDRV.Deliver; delivery result banner

Here is the code that I use in my application.

var client = new SmtpClient
    Host = WebConfigurationManager.AppSettings["EmailHost"],
    Port = 587,
    EnableSsl = true,
    DeliveryMethod = SmtpDeliveryMethod.Network,
    UseDefaultCredentials = false,
    Credentials = new System.Net.NetworkCredential(WebConfigurationManager.AppSettings["EmailSender"],

WebConfigurationManager.AppSettings["EmailHost"], is set to smtp.live.com in the webconfig.

After this, I add data and the other information needed of course, but I omitted that. The error is thrown when we arrive at the last part of the code: client.Send(mail);

Things I have tried so far that did not work.

  • Login to the email account on outlook.live.com;
  • Update security settings on outlook.live.com for the email account;
  • Changed smtp.live.com to smtp-mail.outlook.com;
  • Changed the Port to 25 (which gave me the same error) and 465 (Which gave me a server not reached error);
  • Set EnableSsl to false (Client doesn't work when I do that).

I have seen several posts on SO and other websites that are similar or have the same error code. But they either go unanswered or they mark logging in to the email account as the solution, which does not work for me.

When we logged into the email account we got an update notice from Microsoft talking about the new privacy and security update. This was from September 16th. I don't know if there is a three-month time limit within which you need to agree to it. But a week ago the email account has sent an email, and yesterday it failed on sending one. We agreed to the agreement pop up but it is still not working though.

Does anybody have any idea what I can try now or what is causing this error?

OK, I resolved this issue on my system as follows:

i was sending the message with a different email address to that of the account I was sending from like this:

string from = "email@somwhere.com";

so I changed it to :

string from = "thecorrectemailaddress@outlook.com";

so now it works fine ... happy days

MailMessage mail = new MailMessage(from, to);

Remote Server returned '550 5.2.0 RESOLVER.ADR.BadPrimary' in , "Remote Server returned '550 5.2.0 RESOLVER.ADR.BadPrimary'" error when an Exchange Online user sends mail to an external contact If the user is using Microsoft Outlook to send mail, clear the external contact's name� ¿Viabilidad de C # / .NET como la nueva plataforma de desarrollo de juegos estándar? ¿Por qué .net usa la encoding UTF16 para la cadena, pero usa utf8 como predeterminado para guardar archivos?

The response of a 5.2.0 STOREDEV is because of the SPF on an email server. https://en.wikipedia.org/wiki/Sender_Policy_Framework

What happened here is that when you sent an email from email@somwhere.com your email server attempts to authenticate that the email was legitimate. So it asks somwhere.com what IPs are allowed to send emails claiming to be from somwhere.com, since you don't own somwhere.com it told your email client that it was fraudulent, and your email client rejected it outright as spam.

So when you changed the email to be ...@outlook.com outlook's SPF didn't reject it as spam, and it went through successfully.

Troubleshooting Problems Sending Emails – Donorfy Support, Office 365 The remote server returned an error: (401) Unauthorized. This may Select Outlook at the app you are having problems with. Choose 'I The server response was: 5.3.4 554-554 5.2.0 STOREDRV.Deliver 5.7.57 SMTP; Client was not authenticated to send anonymous mail during mail from. Changed smtp.live.com to smtp-mail.outlook.com Changed the Port to 25 (which gave me the same error) and 465 (Which gave me a server not reached error) Set EnableSsl to false (Client doesn't work when I do that)

I have resolved this issue on my system as follows: The from address should be like these below emails- 1. "thecorrectemailaddress@outlook.com" 2. "thecorrectemailaddress@hotmail.co.uk" Here I am using "smtp.live.com" as server domain and port is 587. If there is any problem with the firewall , you can add a rule in your firewall for the same port 587.

Error sending Mail via MailKit - asp.net-core - php, Here are 2 similar issues: Outlook SMTPClient server error 5.3.4 5.2.0 PHPMailer .Exception:SendAsDeniedException.MapiExceptionSendAsDenied� Simply whitelisting the sender's domain in the spam filter in Exchange admin section of O365 corrected the problem. I was surprised because the error, which refers to "too many hops" detected in the headers, is not a classic indicator of spam, such as falsified information in the header.

C# Send Email with Hotmail (live.com) -- smtp-mail.outlook.com, It expects STARTTLS to establish an explicit TLS connection. Note: When I first tested this code, I received the following error: 550 5.3.4 554-554 5.2.0 STOREDRV� No puedo ver una manera. Puede heredar de la Stack, pero no parece haber nada útil para anular.. La manera fácil (aunque un poco tediosa) sería envolver la Stack con la suya, por ejemplo, LimitedStack.

c# - Outlook SMTPClient服务器错误5.3.4 5.2.0, 在应用程序中,我使用SMTPClient发送电子邮件。 为此,我们使用Outlook电子邮件帐户。 这一直 Outlook SMTPClient server error 5.3.4 5.2.0. A syntax error: the server couldn’t recognize the command. It may be caused by a bad interaction of the server with your firewall or antivirus. Read carefully their instructions to solve it.

User Andie, 17 Outlook SMTPClient server error 5.3.4 5.2.0 Feb 17 '17. 4 Wamp Server 3.0.6 working fine as localhost, but not on network Oct 28 '16. 2 MPDF problems with� 552 5.3.4 Message size exceeds fixed maximum message size NDR returned. If i send a 15 MB file it comes through without issues. below you will see my set limits. We are in a mixed exchange environment. 1 ex2k one ex2k3 and one e2k7. Where could i possibly be missing the setting to allow the emails in?!?!?!?!

  • This also fixed error "5.2.0 STOREDRV.Submission.Exception:SendAsDeniedException.MapiExceptionSendAsDenied; Failed to process message due to a permanent exception with message Cannot submit message."