Hi,

To receive client replies on "Requests for Quotation" emails in Odoo 16 Purchase module, it's essential that the outgoing emails include a properly configured reply_to address. This reply_to should use an email alias like purchase_company@yourdomain.com, which allows Odoo to identify and link incoming replies to the correct purchase order. Additionally, your Incoming Mail Server must be set up to handle these aliases so that replies sent to these addresses are processed correctly by Odoo. Without setting the reply_to field and configuring the incoming mail alias properly, Odoo won't be able to receive or process email replies to purchase orders.

Hope it helps