I found this old node gmail -- sending out html messages which is similar to your TLS code. scorpio17 has posted some warning at the bottom which might be useful.

In reply to Re: Send Email to GMAIL with html body by hdb
in thread Send Email to GMAIL with html body by Maktub

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
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    ] &#93;
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  • See Writeup Formatting Tips and other pages linked from there for more info.