Set Content-Transfer-Encoding to Quoted-printable with .NET MailMessage

4
votes

When i send mails with .NET SmtpClient, i have noticed the content transfer encoding is set to base64 when i check the source code of the mail.

I need to set it to Quoted-printable. How can i achieve this ? Thanks in advance

public virtual MailMessage GetMailMessage(string body, string from, string [] user_emails, string [] back_office_emails, string subject)
{             
    MailMessage message = new MailMessage();
    message.IsBodyHtml = true;
    message.From = new MailAddress(from);            
    foreach (string email in user_emails)
    {
        message.To.Add(new MailAddress(email));
    }            
    if (back_office_emails != null)
    {
        foreach (string email in back_office_emails)
        {
            message.Bcc.Add(new MailAddress(email));
        }
    }
    message.Subject = subject;
    message.Body = body;
    message.BodyEncoding = System.Text.Encoding.UTF8;
    return message;
}

protected virtual void SendEmailTemplate(string body, string from, string[] user_emails, string[] back_office_emails, string subject)
{
    MailMessage message = GetMailMessage(body, from, user_emails, back_office_emails, subject);
    SmtpClient client = new SmtpClient(ConfigurationManager.AppSettings["SmtpClient"]);
    client.Send(message);
}
3
c#.netsmtpclient

3 Answers

3
votes

Because you are setting your message.BodyEncoding to System.Text.Encoding.UTF8, the transfer encoding is automatically set to Base64. (source in remarks section)

Depending on the reason why you need to have Quoted-printable transfer encoding, you will need to adjust your MailMessage object accordingly to have the transfer encoding set to Quoted-printable.

More reading can be done here

1
votes

When using .NET 4.5 or better, it should be possible to use

message.BodyTransferEncoding = System.Net.Mime.TransferEncoding.QuotedPrintable;

See https://docs.microsoft.com/en-us/dotnet/api/system.net.mail.mailmessage.bodytransferencoding?view=netframework-4.5

6
votes

Solution:

AlternateView plainTextView = AlternateView.CreateAlternateViewFromString(body.Trim(), new ContentType("text/html; charset=UTF-8"));
plainTextView.TransferEncoding = System.Net.Mime.TransferEncoding.QuotedPrintable;
message.AlternateViews.Add(plainTextView);