Webmail (Outlook) OVH vs Thunderbird on the same mailbox – no sync

ChristianC4 · June 22, 2026, 2:13pm

Hello,
I am on Debian 13 (gnome) and I have a VPS and a “professional email” with OVH.
I use Thunderbird configured with IMAP/SMTP (pro3.mail.ovh.net) locally for my OVH mailbox and Outlook (the only webmail offered) in a browser for OVH.

I have noticed for a few days that there is no longer any synchronization between Thunderbird and the webmail. Folders appear on one side and not on the other, and vice versa.
I have a huge number of messages that have ended up in spam in the webmail while the folder is empty in Thunderbird.
I have many folders whose labels have turned into labels in the webmail.

It’s incomprehensible.
There was an IMAP/SMTP change some time ago because before pro3.mail.ovh.net, the setting was something like SSL0.ovh.net and everything was OK.

Do you think you can help me?
Thanks in advance.

Asterix · June 22, 2026, 2:21pm

Hello @ChristianC4

I have three questions:

Are you sure that POP was not used during your synchronization(s), which could explain the content difference between the mailbox and webmail.
Have you verified whether the lockout threshold is active in your Email Pro offer: https://docs.ovhcloud.com/fr/guides/web-cloud/email-and-collaborative-solutions/common-email-features/security-policy
Have you tried updating the password of your mailbox, waiting a few minutes, and then attempting to sync your address again in Thunderbird? If needed: https://docs.ovhcloud.com/fr/guides/web-cloud/email-and-collaborative-solutions/email-pro/how-to-configure-thunderbird

Asterix

ChristianC4 · June 22, 2026, 2:36pm

Hello @Asterix, thanks for your responsiveness.

1- I have never used a POP configuration ... for at least 20 years ;o)
2 - I am on the "plan" "MX plan and MX Pro". I have never changed the window that opens and have left these settings at their default forever. Everything is set to "0" except the "minimum password length" which is "8".
3 - I am on LINUX DEBIAN 13 (gnome) and the Thunderbird configuration is almost identical to that on Windows (see your URL). I followed the configuration to the letter.

My sync problem thus persists.

Asterix · June 22, 2026, 2:39pm

In that case, have you already tried updating the email account password? Also, do you have the option to try a sync on another mail client?

Astérix

ChristianC4 · June 22, 2026, 2:43pm

I haven't tried changing the password.

I have, however, tried it on the EVOLUTION software and everything works fine; the sync is OK. I also tried it a while back with CLAWS MAIL and that was OK too.

It's really THUNDERBIRD that is causing the problem!!!

TTY · June 23, 2026, 10:51am

Reset your TB profile, maybe?

ChristianC4 · June 23, 2026, 12:33pm

A priori, according to a user on another forum, you should right‑click the account name and then select “Subscribe”. Then you need to check the boxes next to all the folders.

Since I’ve been using TB for a while I never paid attention to this menu because I never had synchronization problems until today.

I’ll see if this solution fixes my issue.

TTY · June 23, 2026, 3:04pm

Ha, yes exactly! I hadn't thought of that.