Bug#1140099: exim4-daemon-heavy: regression in 4.98.2-1+deb13u3 - bare filename in router domains condition no longer treated as implicit lsearch

[Terry Roy]

Thank you both for the analysis. Based on dpkg.log, deb13u3 was 
installed on 2026-05-30 but the issue was only observed on 2026-06-15 
when an inbound message to an affected address triggered the rejection. 
Adam's diffstat confirms deb13u3 only touched proxy.c.

To clarify Marc's point: his configuration examples use bare filenames 
in a different context from a bare filename used directly in a router 
domains condition. The issue I observed was specifically in the latter case:

   domains = VIRTDIR/domains    # in a router stanza

This may explain why his configuration is unaffected while mine was not.

I've reviewed my configuration changes (tracked with git) for the past 3 
months and nothing has changed in the routers, the aliases file, or any 
other settings that should affect the routers. I added a DNSBL to an acl 
and tweaked a blacklist lookup for another acl. I've run this exact 
setup for years with no issues.

I'm at a loss to explain why this issue arose after the upgrade. I can 
confirm that this alias was receiving mail prior to the upgrade.  The 
fix (adding explicit lsearch; prefix) has enabled that alias to work again.

-- 
Terry