Why send email result is always failure?

Question

I am able to connect with my server using port no 25

 client.Connect("webmail.dataglove-us.com", 25);
 ISendMessageResult result = client.SendMessage(email);

but when sending email its always Failure. can you suggest something?

Comments

Can you please examine ISendMessageResult properties and share its values
-or-
Turn on logging and share the logs:
https://www.limilabs.com/blog/logging-in-ftp-dll

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IsendMessageResult has 5.7.1 Unable to relay Error message in rejectedrecipientError.

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Have you authenticated to this server (UseBestLogin)?

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UseBestLogin giving exception "The remote certificate is invalid according to the validation procedure."

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This means that your server requires client (Mail.dll) to switch to TLS/SSL encrypted channel, before authentication (good thing).

However certificate that the server provides is invalid (not trusted):
Issuer = "C=US, O=dgi, CN=TMAEXEDGE001.dgi.local"

Please read this article:
https://www.limilabs.com/blog/the-remote-certificate-is-invalid-according-to-the-validation-procedure

You should report that to the server administrator.

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i am already using mail.dll , infect i have purchased licence.

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Having a Mail.dll license doesn't change anything - this is not licensing issue.

Certificate provided by this server is simply not valid.

You can always accept invalid certificate (bad thing to do) using this code:

   client.ServerCertificateValidate += (sender, args) => args.IsValid = true;
   client.Connect("webmail.dataglove-us.com", 25);
   client.UseBestLogin("","")

Answer 1

Your server denies sending this email. There can be many reasons for that:

• You have not authenticated to the server, and your server doesn't want to be an open relay.
• You are using port 25 instead of 587 or SSL/TLS connection over 465.

Please note that 25 should not be used for email submission.
Consider not specifying the port at all and using the default one - 587.

Please consult your SMTP server administrator - provide him the logs.