The webmail of Nantes Université relies on centralized authentication (CAS) and separate mail servers depending on the user’s status. When the login page fails to load or loops indefinitely, the cause can range from a simple disabled cookie to a targeted outage on a single domain. Quickly identifying the source of the blockage allows users to retrieve their messages through an alternative route without waiting for the complete restoration of the service.
Academic mail and university mail: a confusion that hinders recovery
Many users type “webmail nantes” into their browser without knowing that there are two completely separate systems. The academic mail (accounts ending in @ac-nantes.fr) was managed by the rectorate through the Webmel service. The university mail (accounts ending in @univ-nantes.fr or @etu.univ-nantes.fr) is managed by the IT department of Nantes Université.
The academic Webmel service was permanently discontinued on January 12, 2026, as part of a migration to other mail solutions for staff in the National Education system. Attempting to connect to this old portal returns an error or a blank page, resembling a failure of the university webmail.
Before any technical manipulation, the first check is to confirm that the address used is indeed associated with Nantes Université and not with the academy. If an access issue to webmail.univ-nantes.fr occurs on an @ac-nantes.fr account, the solution lies with the rectorate or Tchap, not with the university IT department.
Separate IMAP servers for students and staff of Nantes Université
Nantes Université operates distinct infrastructures for its two populations. Staff use the servers imaps.univ-nantes.fr and smtp.univ-nantes.fr. Students go through imaps.etu.univ-nantes.fr and smtp.etu.univ-nantes.fr.
This architecture has a direct consequence: a failure can affect students without impacting staff, and vice versa. When the webmail is unresponsive, the first question to ask on a forum or to support is to specify one’s address domain (@etu or not).
| Element | Staff | Student |
|---|---|---|
| IMAP Server | imaps.univ-nantes.fr | imaps.etu.univ-nantes.fr |
| SMTP Server | smtp.univ-nantes.fr | smtp.etu.univ-nantes.fr |
| IMAP Port (SSL) | 993 | 993 |
| SMTP Port (STARTTLS) | 587 | 587 |
These settings are identical regardless of the email client used (Thunderbird, iOS Mail app, Gmail on Android). Configuring IMAP access remains the most reliable way to retrieve messages even when the web interface is down.
Configuring an IMAP client to bypass a webmail outage in Nantes
The web interface is just one entry point among others to the mailbox. The IMAP protocol allows messages to be synchronized directly from the server, independently of the CAS portal. If the webmail displays a blank page but the IMAP server responds, all emails remain accessible.
Configuration steps on Thunderbird
- Open Thunderbird, then Account Settings, Add Mail Account. Enter the full address (@univ-nantes.fr or @etu.univ-nantes.fr) and the password associated with the university account.
- Enter the incoming server: imaps.univ-nantes.fr (or imaps.etu.univ-nantes.fr for students), port 993, SSL/TLS encryption. The username corresponds to the CAS identifier, without the domain.
- Enter the outgoing server: smtp.univ-nantes.fr (or smtp.etu.univ-nantes.fr), port 587, STARTTLS encryption. Same identifier.
- Validate the configuration and start synchronization. Folders and messages will appear within a few minutes depending on the volume of the inbox.
This method also works on the Mail app of an iPhone or Mac, as well as in the account settings of Gmail on Android. The fields to fill out are the same.
Expired password or locked account: check before blaming the outage
The CAS portal of Nantes Université sometimes displays a generic error message that resembles a server malfunction, while the problem actually lies with the account itself. Two situations frequently arise.
An expired password blocks the connection without prior notification. The reset page is accessible at moncompte.univ-nantes.fr, under the “Forgot Password” section. The procedure requires the personal email address provided during registration.
An account can also be locked after several failed attempts. In this case, online reset may not always suffice. The official site of Nantes Université advises contacting the academic department’s administration (UFR, school, institute) or the IT department via the online support form.
Points to check on the browser side
The CAS login page requires cookies to be enabled. An explicit message (“Cookies Disabled”) appears when the browser blocks them. Ad-blocking or anti-tracking extensions sometimes disable third-party cookies necessary for authentication.
Clearing the browser cache and testing the connection in private browsing can eliminate a session conflict. If the webmail works in private browsing but not in normal mode, the issue stems from an extension or a corrupted cookie.
Cyberattack on National Education: an additional risk of confusion
The start of the 2026 academic year was marked by a cyberattack targeting the digital tools of National Education, disrupting access to services in several academies. Several school leaders and teachers found themselves without access to their professional email for several days.
This attack concerns the services of the Ministry of National Education, not the servers of Nantes Université. The two infrastructures are independent. A staff member of Nantes Université who also uses an academic address (@ac-nantes.fr) may find this latter blocked by the cyberattack without their university account being affected.
Differentiating these two situations helps avoid wasting time contacting the wrong support service. For a university account, the IT department of Nantes Université remains the point of contact. For an academic account, it is the rectorate or the channels of National Education.
Configuring IMAP on a local client remains the most robust method to maintain access to university emails, even during a prolonged outage of the web portal. Keeping these settings configured in advance, before an issue arises, turns a potential emergency into a mere inconvenience.