As stated already you either need to find another SMTP server. Most providers have one for your use, that's unless you plan to use it for spamming. Your other options are to either run your own, provided you have a valid domain or rely on the user’s client using HTML syntex mailto:

In reply to Re: sendmail issue by gman
in thread sendmail issue by Nik

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



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