The filter binary was recompiled but its dependencies (e.g., Perl modules, libssl) are now incompatible with the version Postfix is trying to run.
Dovecot changed the location of its binary or the protocol for LMTP sockets. For example, dovecot-lda (Local Delivery Agent) may have moved from /usr/lib/dovecot/deliver to /usr/libexec/dovecot/dovecot-lda . The filter binary was recompiled but its dependencies (e
The update relabeled binaries or changed file contexts. Postfix may no longer have permission to execute a transport binary. The update relabeled binaries or changed file contexts
sudo journalctl -u dovecot --since "10 minutes ago" sudo journalctl -u spamassassin Scenario 1: Broken Dovecot LMTP or deliver binary Symptom: You updated Postfix but also updated Dovecot from version 2.2 to 2.3 (or similar). The error appears for local or virtual deliveries. The error appears for local or virtual deliveries
This article provides a deep dive into the root causes of this error, specifically focusing on scenarios that arise . We will explore why this happens, how to diagnose the exact issue, and step-by-step solutions to restore normal mail flow. Understanding the Error: What Does It Mean? In Postfix terminology, a transport is the method by which a message is delivered to its final destination. This could be a local mailbox (e.g., using local transport), an LMTP socket, a Dovecot deliver agent, or a relay host (e.g., smtp transport).
Edit /etc/postfix/master.cf and modify the transport line from:
dovecot unix - n n - - pipe To (add v flag and increase verbosity):