% locate libsodium
/opt/homebrew/Cellar/libsodium
/opt/homebrew/Cellar/libsodium/1.0.18_1
/opt/homebrew/Cellar/libsodium/1.0.18_1/.brew
/opt/homebrew/Cellar/libsodium/1.0.18_1/.brew/libsodium.rb
/opt/homebrew/Cellar/libsodium/1.0.18_1/AUTHORS
/opt/homebrew/Cellar/libsodium/1.0.18_1/ChangeLog
/opt/homebrew/Cellar/libsodium/1.0.18_1/INSTALL_RECEIPT.json
/opt/homebrew/Cellar/libsodium/1.0.18_1/LICENSE
/opt/homebrew/Cellar/libsodium/1.0.18_1/README.markdown
/opt/homebrew/Cellar/libsodium/1.0.18_1/include
/opt/homebrew/Cellar/libsodium/1.0.18_1/include/sodium
/opt/homebrew/Cellar/libsodium/1.0.18_1/include/sodium/core.h
/opt/homebrew/Cellar/libsodium/1.0.18_1/include/sodium/crypto_aead_aes256gcm.h
...
/opt/homebrew/Cellar/libsodium/1.0.18_1/include/sodium/utils.h
/opt/homebrew/Cellar/libsodium/1.0.18_1/include/sodium/version.h
/opt/homebrew/Cellar/libsodium/1.0.18_1/include/sodium.h
/opt/homebrew/Cellar/libsodium/1.0.18_1/lib
/opt/homebrew/Cellar/libsodium/1.0.18_1/lib/libsodium.23.dylib
/opt/homebrew/Cellar/libsodium/1.0.18_1/lib/libsodium.a
/opt/homebrew/Cellar/libsodium/1.0.18_1/lib/libsodium.dylib
/opt/homebrew/Cellar/libsodium/1.0.18_1/lib/pkgconfig
/opt/homebrew/Cellar/libsodium/1.0.18_1/lib/pkgconfig/libsodium.pc
/opt/homebrew/lib/libsodium.23.dylib
/opt/homebrew/lib/libsodium.a
/opt/homebrew/lib/libsodium.dylib
/opt/homebrew/lib/pkgconfig/libsodium.pc
/opt/homebrew/opt/libsodium
/opt/homebrew/var/homebrew/linked/libsodium

What do I need to use to stop the:Can't build with libsodium: not found

Sorry these are such stupid questions.

James.

Dovecot uses pkg-config to find out about libsodium, and it seems you're missing libsodium.pc in whatever place mac uses to hide them.

Maybe the .pc file is in the homebrew directory somewhere and needs to be copied, or you can make it yourself. Make sure to change the version and paths.

prefix=/usr
exec_prefix=${prefix}
libdir=${prefix}/lib/x86_64-linux-gnu
includedir=${prefix}/include

Name: libsodium
Version: 1.0.18
Description: A modern and easy-to-use crypto library

Libs: -L${libdir} -lsodium
Libs.private:  -pthread
Cflags: -I${includedir}

Aki

% locate libsodium.pc

/opt/homebrew/Cellar/libsodium/1.0.18_1/lib/pkgconfig/libsodium.pc

/opt/homebrew/lib/pkgconfig/libsodium.pc

/usr/local/lib/pkgconfig/libsodium.pc

prefix=/opt/homebrew/Cellar/libsodium/1.0.18_1

exec_prefix=${prefix}

libdir=${exec_prefix}/lib

includedir=${prefix}/include

Name: libsodium

Version: 1.0.18

Description: A modern and easy-to-use crypto library

Libs: -L${libdir} -lsodium

Libs.private:  -pthread

Cflags: -I${includedir}

prefix=/usr/local

exec_prefix=${prefix}

libdir=${exec_prefix}/lib

includedir=${prefix}/include

Name: libsodium

Version: 1.0.18

Description: A modern and easy-to-use crypto library

Libs: -L${libdir} -lsodium

Libs.private: -lpthread -pthread

Cflags: -I${includedir}