Try this on your email receipt template. Make sure you don't have any funny HTML added if you are copy and pasting (check your HTML source view).

{xsl:value-of select="concat('EUR ', replace(format-number(totalAmountWithTax div quantity * /in/salesOrder/exchangeRate, '##0.00'), '\.', ','))" /}

Hi J T,

It works very good !

Here the output.

Thanks, Ton

Awesome! :)