Horde is the historical webmail deployed on the infrastructure of the Institut Agro Montpellier (formerly SupAgro). For students, researchers, or administrative staff based in Rennes, accessing it requires mastering both the shared CAS authentication and the network constraints related to distance. Here, we detail the technical points that institutional guides do not specify.
CAS Authentication and Network Prerequisites for Horde SupAgro
Access to Horde goes through the CAS (Central Authentication Service) of the Institut Agro Montpellier, hosted on cas.supagro.inrae.fr. This CAS server manages all the digital services of the institution: Horde messaging, ENT, educational platforms.
From Rennes, the connection passes through the RENATER network if you are on a member campus (Agrocampus Ouest, now the Institut Agro Rennes-Angers). In this case, the federated SSO via the Education-Research federation simplifies the procedure: your browser is redirected to the Montpellier CAS after selecting your home institution.
Outside the academic network, from a residential access or a mobile hotspot, the CAS remains accessible but two points deserve attention:
- The TLS certificates of the CAS portal are issued for the domain supagro.inrae.fr. A corporate proxy or a personal VPN that intercepts HTTPS traffic may cause a certificate error and block authentication.
- The CAS session cookie has a limited lifespan. On a high-latency connection (train, saturated 4G), the response time may expire before the ticket validation, resulting in a blank page or a 403 error.
- Browsers configured to delete cookies upon closing systematically invalidate the CAS ticket. You will then need to re-authenticate every time you open a Horde session.
We have documented the complete procedure for connecting to Horde SupAgro from Rennes 17h20, with step-by-step screenshots of the CAS journey.
Accessing Horde SupAgro on the Move Between Rennes and Montpellier
Physical travel between the two campuses remains common for staff with dual assignments or co-supervised doctoral students. There is not always a direct train from Rennes to Montpellier Saint-Roch, which regularly requires a transfer (Paris-Montparnasse then Paris-Lyon, or via Nantes and Lyon Part-Dieu).
During summer construction periods, the situation becomes even more complicated. Local press has reported disruptions on Montpellier tram lines during the summer, with extended travel times on lines 1, 2, and 4. These interruptions complicate the last mile between Saint-Roch station and the Gaillarde campus.
The Last Mile to the Campus
From Montpellier Saint-Roch station, the main campus can be reached by tram. The stop Agropolis, served by tram line 5, is the closest access point for the buildings of the Institut Agro Montpellier. This alternative to line 1 (often busier during peak hours) is worth prioritizing.
To check your Horde emails during the train journey, the onboard Wi-Fi in Euroduplex TGVs works, but the bandwidth is shared among passengers. The Horde webmail, which relies on a relatively lightweight HTML interface, performs better than heavy clients like Thunderbird synchronized via IMAP. We recommend switching Horde to plain text mode to reduce the bandwidth needed for loading messages.
Optimal Mail Client Configuration for Horde SupAgro Montpellier
The Horde web interface remains the recommended access mode by the shared IT service of Montpellier (reachable at [email protected]). However, there is nothing preventing you from configuring a local mail client to access the same mailbox in parallel.
IMAP and SMTP settings are not always published visibly. Here are the settings to apply:
- IMAP server: the server uses port 993 with SSL/TLS encryption. The identifier is that of the CAS (first.last or student ID depending on your profile).
- Outgoing SMTP server: port 587 with STARTTLS is the standard configuration. SMTP authentication uses the same CAS credentials.
- Email aliases (like [email protected] vs [email protected]) must be declared in Horde for replies to be sent from the correct sender address.
- On mobile, the native mail app on iOS or the Gmail app on Android accepts these IMAP/SMTP settings without difficulty, provided you do not enable push synchronization which generates requests too frequently and may trigger a temporary account block.
Managing Calendars and Address Books in Horde
Horde includes a calendar module (Kronolith) and an address book (Turba) accessible via the same CAS session. These modules use CalDAV and CardDAV protocols, allowing for bidirectional synchronization with Thunderbird, Apple Calendar, or DAVx5 on Android.
The CalDAV URL is typically constructed based on the Horde server followed by the path /rpc/calendars/. The main pitfall: the base URL changes if the institution migrates its infrastructure, which has already occurred during the transition from SupAgro to Institut Agro. Check the active URL before configuring a new client.
Troubleshooting Common Errors from a Remote Location
The most reported issues by users in Rennes concern three recurring situations.
The message “Service not authorized” after entering credentials indicates that the Horde service is not registered in the CAS whitelist for your profile. This happens when an account has been created in the Rennes-Angers scope without activating the Montpellier scope. The activation request should be made to the shared IT service.
The “Session expired” error in a loop indicates a third-party cookie issue. Recent browsers (Firefox 120+, Chrome 115+) block third-party cookies by default. Since the SupAgro CAS uses a different domain than Horde, you need to add cas.supagro.inrae.fr to the cookie exceptions in the browser settings.
The IMAP connection refusal from a corporate network often stems from a firewall blocking port 993. A quick test via telnet or openssl s_client on port 993 can confirm whether the blockage is on the local network side or the server side.
The Horde messaging service of the Institut Agro Montpellier remains functional and accessible remotely, provided you master the CAS path and network settings. For staff frequently moving between Rennes and Montpellier, configuring a local IMAP client alongside the web interface offers the best reliability on a daily basis.