The AI agent and AI drafts choose the reply language in different ways. Each one is set separately.
Which language the AI agent replies in
The AI agent replies in the language the customer writes in. It goes by the words in the conversation, not by the customer's email address. Your account's Site language doesn't change it.
To set the language yourself, add a line to your General rules:
- Go to AI agent → Guidance.
- On the General rules card, click Add or Edit.
- Write the rule, for example "Always reply in German." or "Reply in German when the customer writes in German, otherwise in English."
- Click Save.
A language set in General rules wins over the customer's language.
What doesn't set the language:
- Tone of voice. It describes how replies sound, not which language they are in.
- Site language in your account settings.
There is no separate switch or list of allowed languages for the AI agent. The General rules line is the way to do it.
If the AI agent replies in the wrong language
- Check General rules. A line such as "Always use British English" applies to every reply, also to customers who write in another language.
- Check the message you tested with. The AI agent goes by the language of most of the customer's words. A short message that is mostly product names, brand names or quoted English text can get an English reply. Test with a full sentence in the customer's language.
- Check your guidance for quoted sentences. Text in quotes tends to be copied into the reply in the language it was written in. Describe what to do and leave the wording to the AI agent.
The Playground and live conversations pick the language the same way, so a test in the Playground shows what customers will get.
Which language AI drafts are written in
AI drafts are written in the customer's language. They don't use the AI agent's General rules, so a language rule there has no effect on drafts. There is no setting that changes the language of drafts.
To get a draft in another language, select the text in the reply box, click Rewrite with AI, choose Translate to and type the language.