Michael Tsai of C-Command Software has released SpamSieve 2.9.34 with improvements in how the spam filtering utility works with Mail in macOS 10.14 Mojave. The app now better detects when Mail has finished launching before checking that its plug-in is enabled, ensures that SpamSieve detects if macOS has forgotten that you gave SpamSieve Full Disk Access, adjusts the launch agent so that SpamSieve more reliably launches when Mail launches, and protects you from a disabled plug-in when Mail launches after SpamSieve launches (such as when using SpamSieve with multiple mail clients).
SpamSieve 2.9.34 also displays a more helpful error message if Outlook Filter Mailboxes lacks Automation access in Mojave, updates SpamSieve’s code signing for the latest Apple notarization requirements, and fixes a bug where SpamSieve could get confused by the presence of Fluid App instances. If you are using Airmail, you should update to version 3.6.42 or later since Airmail versions 3.6.3 through 3.6.41 are not compatible with SpamSieve when using Mojave. ($30 new with a 20% discount for TidBITS members, free update, 13.9 MB, release notes, macOS 10.7+)