Build dovecot from source

[Horst Simon]

I am sorry if this is not the correct list for asking this. T try to build dovecot 2.3.20 from source on a QNAP NAS, which is a linux variant. There is an dovecot available, but this does not include a pigeonhole sieve,
that’s why I try to build it from source. The configure script works fine, but the make fails as follows:

*** Warning: Linking the executable test-http-payload against the loadable module
*** libssl_iostream_openssl.so is not portable!
libtool: link: gcc -std=gnu99 -g -O2 -fstack-protector-strong -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -mfunction-return=keep -mindirect-branch=keep -Wall -W -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith -Wchar-subscripts -Wformat=2 -Wbad-function-cast -fno-builtin-strftime -Wstrict-aliasing=2 -Wl,--as-needed -o .libs/test-http-payload test-http-payload.o -Wl,--export-dynamic  -L/share/CACHEDEV1_DATA/.qpkg/Entware/lib -L/share/CACHEDEV1_DATA/.qpkg/Apache81/lib ./.libs/libhttp.a ../lib-dns/.libs/libdns.a ../lib-ssl-iostream/.libs/libssl_iostream.a ../lib-master/.libs/libmaster.a ../lib-auth/.libs/libauth.a ../lib-settings/.libs/libsettings.a ../lib-test/.libs/libtest.a ../lib/.libs/liblib.a -ldl ../lib-ssl-iostream/.libs/libssl_iostream_openssl.so -Wl,-rpath -Wl,/opt/lib/dovecot
/opt/bin/ld: ../lib-ssl-iostream/.libs/libssl_iostream_openssl.so: undefined reference to `ENGINE_set_default at OPENSSL_1_1_0'
/opt/bin/ld: ../lib-ssl-iostream/.libs/libssl_iostream_openssl.so: undefined reference to `ENGINE_init at OPENSSL_1_1_0'
/opt/bin/ld: ../lib-ssl-iostream/.libs/libssl_iostream_openssl.so: undefined reference to `ENGINE_load_builtin_engines at OPENSSL_1_1_0'
/opt/bin/ld: ../lib-ssl-iostream/.libs/libssl_iostream_openssl.so: undefined reference to `ENGINE_free at OPENSSL_1_1_0'
/opt/bin/ld: ../lib-ssl-iostream/.libs/libssl_iostream_openssl.so: undefined reference to `ENGINE_finish at OPENSSL_1_1_0'
/opt/bin/ld: ../lib-ssl-iostream/.libs/libssl_iostream_openssl.so: undefined reference to `ENGINE_by_id at OPENSSL_1_1_0'
collect2: error: ld returned 1 exit status
make[3]: *** [Makefile:892: test-http-payload] Error 1
make[3]: Leaving directory '/share/CACHEDEV1_DATA/temp/dovecot-2.3.20/src/lib-http'
make[2]: *** [Makefile:573: all-recursive] Error 1
make[2]: Leaving directory '/share/CACHEDEV1_DATA/temp/dovecot-2.3.20/src'
make[1]: *** [Makefile:702: all-recursive] Error 1
make[1]: Leaving directory '/share/CACHEDEV1_DATA/temp/dovecot-2.3.20'
make: *** [Makefile:546: all] Error 2

I already asked in the GitHub forum, but haven’t received any answers, that why I m asking here if anyone can help me to get it working.

Horst