The Debian packaging of mairix is maintained in git, using the merging
workflow described in dgit-maint-merge(7).  There isn't a patch queue
that can be represented as a quilt series.

A detailed breakdown of the changes is available from their canonical
representation - git commits in the packaging repository.  For
example, to see the changes made by the Debian maintainer in the first
upload of upstream version 1.2.3, you could use:

    % git clone https://git.dgit.debian.org/mairix
    % cd mairix
    % git log --oneline 1.2.3..debian/1.2.3-1 -- . ':!debian'

(If you have dgit, use `dgit clone mairix`, rather than plain `git
clone`.)

A single combined diff, containing all the changes, follows.
--- mairix-0.24+git20260522.orig/configure
+++ mairix-0.24+git20260522/configure
@@ -438,18 +438,18 @@ if [ "x" = "x${DOCDIR}" ]; then DOCDIR=$
 echo "Generating Makefile"
 
 rm -f Makefile
-sed -e "s%@cc@%${MYCC}%; \
-        s%@defs@%${DEFS}%; \
-        s%@cflags@%${MYCFLAGS}%; \
-        s%@prefix@%${PREFIX}%; \
-        s%@bindir@%${BINDIR}%; \
-        s%@mandir@%${MANDIR}%; \
-        s%@infodir@%${INFODIR}%; \
-        s%@datadir@%${DATADIR}%; \
-        s%@docdir@%${DOCDIR}%; \
-        s%@LIBS@%${LIBS}%; \
-        s%@CPPFLAGS@%${MYCPPFLAGS}%; \
-        s%@LDFLAGS@%${MYLDFLAGS}%; \
+sed -e "s|@cc@|${MYCC}|; \
+        s|@defs@|${DEFS}|; \
+        s|@cflags@|${MYCFLAGS}|; \
+        s|@prefix@|${PREFIX}|; \
+        s|@bindir@|${BINDIR}|; \
+        s|@mandir@|${MANDIR}|; \
+        s|@infodir@|${INFODIR}|; \
+        s|@datadir@|${DATADIR}|; \
+        s|@docdir@|${DOCDIR}|; \
+        s|@LIBS@|${LIBS}|; \
+        s|@CPPFLAGS@|${MYCPPFLAGS}|; \
+        s|@LDFLAGS@|${MYLDFLAGS}|; \
        " < Makefile.in > Makefile
 
 # Avoid editing Makefile instead of Makefile.in
--- mairix-0.24+git20260522.orig/mairix.1
+++ mairix-0.24+git20260522/mairix.1
@@ -1,3 +1,4 @@
+'\" t
 .TH MAIRIX 1 "January 2006"
 .de Sx
 .PP
