Delivery Temporarily Suspended Unknown Mail Transport Error Postfix Upd -

dovecot unix - n n - - pipe To (add v flag and increase verbosity):

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.

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). dovecot unix - n n - - pipe

dovecot unix - n n - - pipe flags=DRhu user=vmail argv=/usr/libexec/dovecot/dovecot-lda -f $sender -d $user@$domain -o plugin/quota=maildir:User quota -d Also, increase Postfix’s global verbosity:

The key to resolution is identifying the specific transport (pipe, LMTP, smtp) that is failing, checking the system logs for underlying errors, and verifying that the external binary or socket is functional when invoked manually by the postfix user. We will explore why this happens, how to

The update relabeled binaries or changed file contexts. Postfix may no longer have permission to execute a transport binary.

Procmail (or the custom binary) was removed or replaced by a stub that returns a non-zero exit code. Many distributions removed Procmail by default after 2020. This could be a local mailbox (e

By methodically isolating the transport—whether Dovecot, Amavis, Maildrop, or a custom script—you can convert the "unknown" into a known, actionable fix. And once resolved, safeguard your configuration to ensure that the next system update doesn’t leave your mail queue suspended once again.