numeric username

[Jernej Porenta]

Heya,

does dovecot support "numeric only" usernames (in format "^0-9+$")?

We are unable to deliver emails to such usernames via LMTP:
Sep 22 08:41:05 razor4 postfix/lmtp[2120]: D4FD91CDC11F:
to=<231588 at example.org>, relay=example.org[private/dovecot-lmtp],
delay=217653, delays=217653/0.01/0.02/0, dsn=4.2.0, status=deferred
(host example.org[private/dovecot-lmtp] said: 451 4.2.0
<231588 at example.org> Permission denied (in reply to end of DATA command))

On normal username format (^[a-z][-a-z0-9]+$) everything is working fine.

Permissions are the same as on other accounts:
# ls -la .mailbox
-rw-------+ 1 231588 users 0 Sep 19 20:13 .mailbox

Using dovecot 2.2.13 with local accounts on RHEL and (relevant) configs:
auth_username_chars =
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@
auth_username_format = %Ln
auth_username_translation =
...
lmtp_address_translate =
...
passdb {
args = cache_key=%u%s dovecot
default_fields =
deny = no
driver = pam
master = no
name =
override_fields =
pass = no
result_failure = continue
result_internalfail = continue
result_success = return-ok
skip = never
}
...
service lmtp {
chroot =
client_limit = 1
drop_priv_before_exec = no
executable = lmtp
extra_groups =
group =
idle_kill = 0
privileged_group =
process_limit = 0
process_min_avail = 5
protocol = lmtp
service_count = 0
type =
unix_listener /var/spool/postfix/private/dovecot-lmtp {
group = postfix
mode = 0600
user = postfix
}
unix_listener lmtp {
group =
mode = 0666
user =
}
user =
vsz_limit = 18446744073709551615 B
}
....
userdb {
args =
default_fields =
driver = passwd
name =
override_fields =
result_failure = continue
result_internalfail = continue
result_success = return-ok
skip = never
}

Thank you in advance,

cheers, Jernej