Why don't emails from Odoo reach customers?
Usually the receiving server does not trust your mail. Odoo sends on behalf of your domain, and if your domain does not say Odoo may do that, the mail ends up in spam or gets rejected.
Since February 2024, Google and Yahoo require anyone sending a lot of mail to have SPF, DKIM and DMARC in order, and Microsoft followed in 2025. An Odoo that mailed fine for years can suddenly produce complaints without anything changing in Odoo.
How do you check that your domain is set up for Odoo?
Look at SPF, DKIM and DMARC in your DNS. On Odoo Online your SPF record needs include:_spf.odoo.com; the DKIM setting is in Odoo's documentation on configuring your email domain.
Then send a mail from Odoo to a tester such as mail-tester.com. It shows per record what is missing. Five minutes, and it saves you an afternoon of guessing.
Why does Odoo send from a notification address?
By default Odoo sends from its own sender address and catches replies through a catchall address. That is how a customer's reply finds its way back to the right record.
The downside is that the customer sees a different address than yours. It looks like a robot, and some spam filters agree.
Can Odoo send through your own Outlook or Gmail?
Yes. In Odoo you can set Microsoft 365 or Gmail as the outgoing mail server. Your own provider then sends the mail, from your own domain.
Mail Pro, which we build, goes a step further: mail leaves from the mailbox of whoever sends it, or from a shared mailbox such as sales@, and then sits in your Sent Items like any other mail. Replies land back on the quote or ticket they belong to. It works with Odoo 19 on Odoo.sh, Cloudpepper or your own server; the beta opens in October. How it compares to MailDesk is in Mail Pro vs MailDesk.
What if only some customers don't get your mail?
Then the problem is often on their side, in a strict spam filter or an IT quarantine. Ask them to check spam and quarantine and to mark your domain as a trusted sender.
If it keeps failing for the same few customers while the tester is green, your side is probably fine.