Is Smarty processing also available for sending single mails which are not a part of a mass mailing?

Question

I try to send a single mail through Contacts > New Mail using a template containing next Smarty instructions:

{if {contact.preferred_language} == "fr_FR"}OK{else}KO{/if}

but these mails cause an error with a very cryptic message:

Error

The website encountered an unexpected error. Please try again later.

EDIT: Thanks to Demerit (see below), I could identify what is working and what not. The smarty code

{capture assign=pref}{contact.preferred_language}{/capture}

{contact.email_greeting} ({contact.preferred_language} = {$pref}?),

is working as expected and gives the expected output

Monsieur (fr_FR = fr_FR?),

So, the {capture}instruction is working, but when I add the instruction below

{if $pref == "fr_FR"}OK{/if}

I get the error message described above and no message is sent.

Answer 1

Thanks for pasting the code: You can't use tokens inside a smarty command like that.

You need to do:

{capture assign=pref}{contact.preferred_language}{/capture}
{if $pref == "fr_FR"}OK{else}KO{/if}