Mandrill "reject_reason": "invalid-sender"

Question

I'm trying to send emails using mandrill email service but I get the following error

    Full Response
[
    {
        "email": "someemail@somedomain.com",
        "status": "rejected",
        "_id": "b814c2974594466cba9c904c54dca6c6",
        "reject_reason": "invalid-sender"
    }
]

Apart from the above error there is no more details about it. we are using .net to send emails with Mandrill SMTP settings.

user_2682748 · Answer

If you use .NET SmtpClient, may be this is because of bug on it: https://social.msdn.microsoft.com/Forums/vstudio/en-US/4d1c1752-70ba-420a-9510-8fb4aa6da046/subject-encoding-on-smtpclientmailmessage

Workaround, that helped us:

use

message.SubjectEncoding = Encoding.Unicode;

instead of

message.SubjectEncoding = Encoding.UTF8;

This is still actual in .Net Framework 4.7.2

Mandrill "reject_reason": "invalid-sender"

6 Answers