
Try the following...
Add a successMessage hook:
[[!FormIt?
&hooks=`spam,email`
&emailTpl=`contactEmailTpl`
...
&successMessage=`Thanks!`
]]
Add a placeholder below the FormIt tag:
[[+fi.successMessage]]
Remember not to use redirect hook for it to work!
Everything is nicely explained here:
http://rtfm.modx.com/display/ADDON/FormIt

[[!FormIt?
&hooks=`recaptcha,spam,email,emailSubject`
&recaptchaJs=`{"lang":"[[++cultureKey]]", "theme":"blackglass"}`
&emailTpl=`ContactoEmail`
&emailFrom=`[[+ecorreo]]`
&emailFromName=`[[+nombre]]`
&emailTo=`[email protected]`
&emailSubject=`Mensaje desde el sitio web - www.jsarquitectura.com`
&successMessage=`Thanks!`
&validate=`
nospam:blank,
nombre:required,
ecorreo:email:required,
mensaje:required:stripTags`
]]
<div id="formcontacto">
<form name="formcontacto" action="[[~[[*id]]]]" method="post">
<input type="hidden" name="nospam" value="" />
<p>
<label for="nombre" class="formcontacto">Nombre[[+fi.error.nombre]]</label>
<input name="nombre" id="nombre" type="text" tabindex="1" value="[[+fi.nombre]]" />
</p>
<p>
<label for="ecorreo"class="formcontacto">Correo electrónico[[+fi.error.ecorreo]]</label>
<input name="ecorreo" id="ecorreo" type="text" tabindex="1" value="[[+fi.ecorreo]]" />
<p>
<span class="formcontacto">Mensaje[[+fi.error.mensaje]]</span>
<textarea name="mensaje" id="mensaje" cols="25" rows="7" value="[[+fi.mensaje]]" class="input-msg">[[+fi.mensaje]]</textarea>
</p>
<p>
[[!+formit.recaptcha_html]]
[[!+fi.error.recaptcha]]
</p>
<button type="submit">Enviar</button>
</form>
</div>
[[+fi.successMessage]]Parse error: syntax error, unexpected T_STRING in /home/content/54/8603754/html/modx/core/cache/includes/elements/modsnippet/31.include.cache.php on line 7
$modx->setPlaceholder('successMessage','Form submitted successfully.');
return true;[[!FormIt? &hooks=`recaptcha,spam,email,formitSuccess` ... ]] [[!+successMessage:notempty=`[[!+successMessage]]`]]
[[+fi.successMessage]]