This package currently fails to build (at least on the amd64
architecture) with link time optimizations enabled.  For a background
for LTO please see

https://wiki.debian.org/ToolChain/LTO

The goal is to enable this optimization by default in an upcoming
Debian release in dpkg-buildflags for 64bit architectures.  The goal
is to get this package to build with link time optimizations, or to
explicitly disable link time optimizations for this package build.

To reproduce the build failure, enable the lto optimization in
testing/unstable by adding "optimize=+lto" to DEB_BUILD_MAINT_OPTIONS
in the debian/rules file, or if this macro is unset, just set it:

export DEB_BUILD_MAINT_OPTIONS = optimize=+lto

Please try to fix the build with lto enabled, fixing the packaging or
forwarding the issue upstream. If the issue cannot be fixed,
explicitly disallow building the package with lto by adding to your
rules file:

export DEB_BUILD_MAINT_OPTIONS = optimize=-lto

or adding that string to your existing setting of DEB_BUILD_MAINT_OPTIONS.

The full build log can be found at:
http://qa-logs.debian.net/2022/06/09/dpkglto/mairix_0.24-2_unstable_dpkglto.log
The last lines of the build log are at the end of this report.

[...]
	echo "passed" >55-numeric-subfolder-name.status || \
	echo "Test 55-numeric-subfolder-name.test-spec did not succeed."
make[4]: Entering directory '/<<PKGBUILDDIR>>/test'
rm -rf 55-numeric-subfolder-name.data
scripts/test.sh 55-numeric-subfolder-name.test-spec
log: == add_messages mh 99 == (line: 6)
log: == assert_no_more_matches  == (implicitly added)
make[4]: Leaving directory '/<<PKGBUILDDIR>>/test'
scripts/print_test_statistics.sh

========================================================
--------1*----------------------------------------------
failed: 10-add-messages-maildir
failed: 10-add-messages-mbox
passed: 10-add-messages-mh
failed: 15-add-messages-all-formats
--------2*----------------------------------------------
failed: 20-remove-purge-messages-maildir
failed: 20-remove-purge-messages-mbox
failed: 20-remove-purge-messages-mh
--------3*----------------------------------------------
failed: 30-mformat-maildir
failed: 30-mformat-mbox
failed: 30-mformat-mh
--------4*----------------------------------------------
passed: 40-search-attachments
failed: 40-search-body-exact
passed: 40-search-cc-header
passed: 40-search-date-header-left-closed-right-closed
passed: 40-search-date-header-left-closed-right-open
passed: 40-search-date-header-left-open-right-closed
failed: 40-search-exact
passed: 40-search-flags
passed: 40-search-from-header
passed: 40-search-msg-id
passed: 40-search-size-left-closed-right-closed
passed: 40-search-size-left-closed-right-open
passed: 40-search-size-left-open-right-closed
passed: 40-search-subject-header
failed: 40-search-substring-exact
failed: 40-search-substring-exact-word-start
failed: 40-search-substring-fuzz
failed: 40-search-substring-fuzz-word-start
failed: 40-search-thread
passed: 40-search-to-header
failed: 45-search-combinations
passed: 45-search-in-more-than-one-part
failed: 45-search-negations
--------5*----------------------------------------------
passed: 50-search-and-or
passed: 55-numeric-subfolder-name

========================================================

  Total # of tests           : 35
  Total # of succeeded tests : 17
  Total # of failed tests    : 18

========================================================

make[3]: *** [Makefile:74: check] Error 18
make[3]: Leaving directory '/<<PKGBUILDDIR>>/test'
make[2]: *** [Makefile:115: check] Error 2
make[2]: Leaving directory '/<<PKGBUILDDIR>>'
dh_auto_test: error: make -j1 check "TESTSUITEFLAGS=-j1 --verbose" VERBOSE=1 returned exit code 2
make[1]: *** [debian/rules:16: override_dh_auto_test] Error 25
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:6: build] Error 2
dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2