The academic messaging system ac-lyon.fr presents recurring difficulties, most of which stem from three specific technical causes: a login ID that is different from the email address, incorrectly specified encryption settings, and a persistent confusion between the various Lyon portals. We detail here the actual blocking points and the fixes that work.
IMAP ID different from the email address: the source of most connection failures
On the messaging system ac-lyon.fr, the login ID (pnom) does not correspond to the email address. The ID follows the format first letter of the first name + last name (for example, “jdupont”), while the full address is [email protected]. Almost all mail clients (Outlook, Thunderbird, iOS and Android applications) pre-fill the ID field with the full email address. If you do not manually correct this field, authentication fails without an explicit error message.
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We recommend always checking the “username” or “ID” field after automatic configuration. Configuration assistants detect the domain ac-lyon.fr but apply the standard convention ID = address, which does not work here.
For those looking to resolve messaging issues at ac Lyon, this ID/address distinction remains the first point to check before any other manipulation.
IMAP and SMTP settings: encryption and ports to be entered manually
Emails are transmitted encrypted between the terminal and the academic server. This layer of security imposes precise settings that the automatic detection of mail clients does not always find.
Here are the settings to enter for correct operation:
- IMAP incoming server: imap.ac-lyon.fr, port 993, SSL/TLS encryption. The POP3 protocol also works (port 995, SSL/TLS), but IMAP remains preferable for synchronizing multiple devices.
- SMTP outgoing server: smtp.ac-lyon.fr, port 465 in SSL/TLS or port 587 in STARTTLS. Port 25, unencrypted, is blocked by most ISPs and should no longer be used.
- SMTP authentication must be enabled with the same pnom ID and the academic password. Without this activation, sending fails even if receiving works.
On iOS, the configuration goes through Settings > Mail > Accounts > Other. On Android, the Gmail app or the native mail app offers “Other” or “IMAP” after automatic detection fails. In both cases, each parameter must be entered manually.
Confusion between Lyon portals: academic webmail, ENS, and universities
Lyon concentrates several academic messaging systems that have nothing in common technically. Using the wrong portal is a frequent mistake, especially for staff involved in multiple institutions.
- National Education staff fall under webmail.ac-lyon.fr, which is the only valid entry point in 2026. Old addresses are obsolete, redirected, or potentially dangerous.
- ENS de Lyon uses webmail.ens-lyon.fr with centralized CAS authentication, incompatible with academic IDs.
- The universities Lyon 1, Lyon 2, and Lyon 3 each have their own system: SESAME at Lyon 1, centralized authentication at Lyon 2, institutional account at Lyon 3.
If you attempt to connect to webmail.ac-lyon.fr with university credentials (or vice versa), the portal rejects the connection without specifying that the problem lies with the authentication system itself. Checking that the portal corresponds to your status eliminates a significant portion of the reported blocks.
Full mailbox and storage quota: a silent problem on ac Lyon messaging
The official documentation from DRANE reminds users to regularly check the webmail to ensure that the mailbox is not full. The problem is that exceeding the quota blocks incoming mail without notification. Senders sometimes receive a rejection message, sometimes not. On your side, no alert appears on the mail client configured in IMAP: old messages remain visible, but new ones no longer arrive.
The only reliable way to check the quota status is to log in directly to webmail.ac-lyon.fr via a browser. The interface displays the used space. If the quota is reached, we recommend prioritizing the deletion of messages with large attachments, then emptying the trash (which consumes quota until it is purged).
Academic password and NUMEN: reset without going through support
The password for the messaging system ac-lyon.fr is the academic password, which is also used to access I-Prof and other academy services. After changing the password on the arena portal or via I-Prof, all configured mail clients must be updated manually. The new password does not automatically propagate to Thunderbird, Outlook, or mobile applications.
In case of forgetting, the reset procedure goes through the academic portal and requires the NUMEN (personal identifier for National Education). If you cannot find either your password or your NUMEN, the administration of your institution or the personnel management service can provide the NUMEN. The academic technical support intervenes as a last resort.
A detail often overlooked: after resetting, the new password may take a few minutes to propagate on the IMAP server. Testing the connection immediately via webmail before reconfiguring mail clients avoids multiplying failed attempts, which can trigger a temporary account lockout.