the dependency to sqlite3 seems to be missing? synth logfile: ... checking for valgrind... no checking pkg-config is at least version 0.25... yes checking for ICU_UC... yes checking for ICU_I18N... yes checking for SQLITE3... no configure: error: SQLite3 missing after adding LIB_DEPENDS+=libsqlite3.so:databases/sqlite3 to the Makefile it builds just fine.
You didn't specify exact port version, but judging by the reported date of 2020-04-15 it should be ~1.3 when they've briefly used SQlite to handle expunges outside Xapian, as Xapian does not explicitly handle concurrency, per the discussion in the linked upstream issue. SQLite is no longer used since October 20, 2020. The port is currently at version 1.4.11 and builds fine; the latest version is 1.4.12 (maintainer CC'ed). That said, I'm closing this PR.