Thanks to Johannes for the notification
<img src="i/exim-book.png" width="74" height="100"/>
</a>
<xsl:text>You may wish to purchase </xsl:text>
- <a href="https://www.uit.co.uk/the-exim-smtp-mail-server">The Exim SMTP Mail Server</a>
+ <a href="https://www.uit.co.uk/the-exim-smtp-mail-server.html">The Exim SMTP Mail Server</a>
<xsl:text> book, written by the original author of Exim, </xsl:text>
<a href="https://en.wikipedia.org/wiki/Philip_Hazel">Philip Hazel</a>
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