Thanks for the suggestions but I am not sure whether this can be achieved in the Email Form Plugin, Options tab > Message Text box.
Note: the {mysql_date} placeholder does insert the full timestamp. Not sure what code will split the year from the timestamp in the message box.
Here is the part of text using the element placeholders and where I am trying to insert the 'year' part of the timestamp.
<div><span style="font-family: arial,helvetica,sans-serif; font-size: 12pt;"><strong>{calendar___Event}</strong> being conducted at<strong> {calendar___Location}</strong></span>
</div>
<div><span style="font-family: arial,helvetica,sans-serif; font-size: 12pt;">and commencing on the<strong> {calendar___StartDate} </strong>and finishing on the<strong> {calendar___enddate},
$date = '{mysql_date}'; $year = explode("-",$date) [0]; return $year; </strong></span>
</div>
Steve