Attaching HTML email signature to plain text email body in C#

I wrote a program to send reminder emails to some of our customers, and it works. Now we are trying to add our email signature to our e开发者_开发技巧mails which is an html file. We are using the same file in Thunderbird. I tried adding the HTML content to the body and it works. The only problem is "\n" doesn't work as newline anymore, since smtpClient.IsBodyHtml = true ! tried replacing "\n" with <br /> didn't work, but including the actual message inside the body of my html signature works fine, except mail servers detect them as spam mails ! is there any solution to this ? My actual email is a plain text I just want to add the logo of our company linked to our website to the end.

I sympathise with you as you only want a plain text email but if your clients really want those emails and you really want your logo in then they could just white list your domain so that all emails get through!

We use a company called mailchimp for sending out subscriber mails and I questioned them on how to avoid spam filters especially in the context of essentially an advert out to a large group it can be very difficult to avoid them, here is their advice and there is lots of it.;

Avoiding the Spam Filters