Hi,
The external subscription form does not load any data from your Acymailing server. Instead, it simply renders and presents the form to the user. Therefore, it is vital that the options for the dropdown field are added directly to the external subscription form.
When adding the options for the dropdown field, please keep in mind that values in the database are stored using the official language notations. For example, the correct value for English should be "en-GB".
Example:
<label for="language">Language</label>
<select name="language" id="language">
<option value="en-GB">English</option>
<option value="nl-NL">Dutch</option>
</select>