Safari and Chrome webmail login at webmail.domain.tld redirects back to login page

Symptoms

After entering valid credentials at the webmail proxy subdomain (webmail.domain.tld) in Safari on iOS or macOS, the page redirects back to the login page instead of opening the inbox. Firefox, Chrome, and Android browsers are not affected. Accessing webmail via the hostname URL or port 2096 directly is also not affected.

Cause

The "Jail Apache Virtual Hosts" tweak (mod_ruid2) is enabled on the server. This causes webmail's login session cookie to be restricted to port 2095. Safari enforces this restriction and cannot deliver the session cookie to the post-login redirect, which uses port 443, causing the login to fail.

Resolution

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-56622. Follow this article to receive an email notification when a solution is published in the product.

In the interim, webmail can be accessed in Safari or Chrome using either of the following URLs, which bypass the proxy subdomain:

1. In Safari, or Chrome navigate to https://hostname.domain.tld/webmail
2. Log in with the full email address and password.

Or:

1. In Safari, navigate to https://hostname.domain.tld:2096
2. Log in with the full email address and password.

Optionally, mod_ruid2 can be removed via EasyApache if needed.