Documentation Restructure

services/email/iredmail/query-smtp-outgoing-queue.md

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+## Purpose
+You may need to troubleshoot the outgoing SMTP email queue / active sessions in iRedMail for one reason or another.  This can provide useful insight into the reason why emails are not being delivered, etc.
+
+### Overall Queue Backlog
+You can run the following command to get the complete backlog of all email senders in the queue.  This can be useful for tracking the queue's "drainage" over-time.
+
+```sh
+# List the total number of queued messages
+postqueue -p | egrep -c '^[A-F0-9]'
+
+# Itemize and count the queued messages based on sender.
+postqueue -p | awk '/^[A-F0-9]/ {id=$1} /from=<[^>]+>/ && $0 !~ /from=<>/ {print id; exit}'
+```
+
+!!! example "Example Output"
+    - 10392 problematic@bunny-lab.io
+    - 301 prettybad@bunny-lab.io
+    - 39 infrastructure@bunny-lab.io
+    - 20 nicole.rappe@bunny-lab.io
+
+### Investigating Individual Emails
+You can run the following command to list all queued messages: `postqueue -p`.  You can then run `postcat -vq <message-ID>` to read detailed information on any specific queued SMTP message:
+
+```sh
+postqueue -p
+postcat -vq 4dgHry5LZnzH6x08 # (1)
+```
+
+1.  Example message ID gathered from the previous `postqueue -p` command.
+
+### Attempt to Gracefully Reload Postfix
+You may want to try to unstick things by gracefully "reloading" the postfix service via `postfix reload`.  This will ensure that we don't drop / disconnect / lose all of the active outgoing SMTP sessions in the queue.  It may not help resolve issues, but it's worth noting down:
+
+### Reattempt Delivery
+You can attempt redelivery via running `postqueue -f` to try to free up the queue.  Postfix will immediately re-attempt delivery of all queued messages instead of waiting for their scheduled retry time. It does not override remote rejections or fix underlying delivery errors; it only accelerates the next delivery attempt.