C.7 Upgrading from 8.2 to 8.3 (or 8.4)

Versions 8.3 and 8.4 differ only in required minimal version of mailutils (3.3 and 3.4, correspondingly). Apart from that, the following instructions apply to both versions.

In version 8.3 I abandoned the legacy DNS resolver and switched to GNU adns. GNU ands is a standalone resolver library, which provides a number of advanced features. It is included in most distributions. The source code of the recent release is available from http://www.chiark.greenend.org.uk/~ian/adns/adns.tar.gz.

This change brought a number of user-visible changes. In particular, arbitrary limits on the sizes of the RRs are removed. Consequently, the following configurations statements are withdrawn:

runtime.max-dns-reply-a

runtime.max-dns-reply-ptr

runtime.max-dns-reply-mx

max-match-mx

max-callout-mx

Secondly, the new resolver is less tolerant to deviations from the standard. This means that remote DNS misconfigurations that would have slipped unnoticed in previous versions, will be noticed by mailfromd 8.3. For example, a CNAME record pointing to another CNAME is treated as an error.

A new command line option was added to mailfromd and calloutd: --resolv-conf-file. This option instructs the programs to read resolver settings from the supplied file, instead of the default /etc/resolv.conf.

Another user-visible change is in handling of SPF checks. Previously, results if SPF checks were cached in a database. This proved to cause more problems than solutions and was removed in this version. As a result, the following MFL global variables have been withdrawn:

spf_ttl

spf_cached

spf_database

spf_negative_ttl