/usr/include/GNUstep/NGMime/ is in libsope-dev 2.2.17-1build2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/GNUstep/NGMime/NGConcreteMimeType.h
/usr/include/GNUstep/NGMime/NGMime.h
/usr/include/GNUstep/NGMime/NGMimeBodyGenerator.h
/usr/include/GNUstep/NGMime/NGMimeBodyParser.h
/usr/include/GNUstep/NGMime/NGMimeBodyPart.h
/usr/include/GNUstep/NGMime/NGMimeBodyPartParser.h
/usr/include/GNUstep/NGMime/NGMimeDecls.h
/usr/include/GNUstep/NGMime/NGMimeExceptions.h
/usr/include/GNUstep/NGMime/NGMimeFileData.h
/usr/include/GNUstep/NGMime/NGMimeGeneratorProtocols.h
/usr/include/GNUstep/NGMime/NGMimeHeaderFieldGenerator.h
/usr/include/GNUstep/NGMime/NGMimeHeaderFieldParser.h
/usr/include/GNUstep/NGMime/NGMimeHeaderFields.h
/usr/include/GNUstep/NGMime/NGMimeJoinedData.h
/usr/include/GNUstep/NGMime/NGMimeMultipartBody.h
/usr/include/GNUstep/NGMime/NGMimePartGenerator.h
/usr/include/GNUstep/NGMime/NGMimePartParser.h
/usr/include/GNUstep/NGMime/NGMimeType.h
/usr/include/GNUstep/NGMime/NGMimeUtilities.h
/usr/include/GNUstep/NGMime/NGPart.h
/usr/include/GNUstep/NGMime/NSData+RFC822.h