List Mailboxes Storage and Passwords

List Mailboxes and Size

You can find list of mailboxes and space taken by each of them using following command/script (source):

 if [ -d /var/qmail/mailnames ]; then echo -ne "\n\n=== MAILBOXES ===\n"; cd /var/qmail/mailnames && TMB=$(du -ks */* 2>/dev/null | sort -nr | cut -f2); if [ -n "$TMB" ]; then echo "$TMB" | xargs du -sh; fi; echo "[`find . -mindepth 2 -maxdepth 2 -type d | wc -l` Mailboxes - Total `du -hs | cut -f1`]"; fi;

It will generate output like:

=== MAILBOXES ===
3.6M	example.com/bob
3.3M	rtcamp.com/joe
[2 Mailboxes - Total 3.9M]

List Mailboxes and Passwords

Plesk has builtin command for this. Simply run:

/usr/local/psa/admin/bin/mail_auth_view

And you will see something like:

+------------------ ---+-----+---------------+
|       address        |flags|   password    |
+----------------------+-----+---------------+
|    [email protected]   |     |     hello     |
|    [email protected]    |     |     world     |
+----------------------+-----+---------------+
Flags
	A - account disabled
	D - domain disabled
	E - password encrypted

Mail Queue

Pleak has another built-in command to inspect mailqueue.

Running /usr/local/psa/admin/bin/mailqueuemng will show useful help about different parameters.

References

Check this for awesome collection of Plesk commands and cheats.