To prevent emails fetched from the incoming mail server from being automatically logged in the CRM chatter in Odoo, you can control this behavior at several levels, depending on your setup.

Here are the key options to prevent it

Option 1: Disable Auto-Followers or Auto-Threading

Odoo links incoming emails to existing records by matching the email's headers (Message-ID, References, etc.) or aliases. If you don’t want them to be added to the CRM chatter:

A. Remove aliases from CRM

Go to CRM > Configuration > Pipelines > Stages

Check if any alias is set up (like leads@yourdomain.com)

Remove or change the alias

B. Disable "Create a new record" in the alias settings

Go to Settings > Technical > Email > Aliases

Find the alias related to CRM

Set Action to Do nothing or Unlink it from CRM objects

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Option 2: Modify Fetchmail or Mail Thread Behavior via Code

If you need finer control (e.g., allow emails in Helpdesk but not in CRM), override the mail handling logic:

Example: Override message_route or message_new to exclude CRM

from odoo.addons.mail.models.mail_thread import MailThread

from odoo import models

class CustomMailThread(MailThread):

    def message_route(self, message, message_dict, model=None, thread_id=None, custom_values=None):

        # Skip processing if it's for crm.lead

        if model == 'crm.lead':

            return []

        return super().message_route(message, message_dict, model, thread_id, custom_values)

This prevents emails from being routed to crm.lead.

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Option 3: Use Domain Filtering in Incoming Mail Server

You can add filters to avoid processing certain messages altogether.

Go to Settings > Technical > Email > Incoming Mail Servers

Open your mail server

Add custom Python code in the Actions to Perform on Incoming Mails (e.g., skip based on subject or sender)

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Option 4: Unsubscribe System from Threads

Sometimes, Odoo posts email replies to CRM because the system user is a follower. You can:

Disable automatic followers in CRM settings

Or programmatically unsubscribe users from records

lead.message_unsubscribe([user_id])

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If you tell me how your mail server is configured or how you receive CRM messages (e.g., via alias, manually, automated integration), I can tailor the solution more precisely.