user abc@domain1
+OK USER abc@domain1 set, mate
pass abc
-ERR failed: Could not determine server
Oct 17 09:09:53 perdition[19887]: Auth: client-secure=plaintext authorisation_id=NONE authentication_id="abc@domain1" server="(null):pop3" protocol=POP3 server-secure=plaintext status="failed: Could not determine server"

I am going to explain it with the real domains involved and my real config file:

Perdition version: perdition-1.17-1

perdition -i -F - -M /usr/lib/libperditiondb_posix_regex.so

Oct 17 16:43:08 perdition[29321]: Connect: inetd_pid=28275
+OK POP3 Ready e_entrada1 0001cbb7
USER prueba@lynzos.com
+OK USER prueba@lynzos.com set, mate
PASS XXXX
-ERR Re-Authentication Failure

In the backend server:

Oct 17 16:43:41 buzones_externos dovecot: pop3-login: Aborted login (auth failed, 1 attempts): user=<prueba>, method=PLAIN, rip=192.168.1.13, lip=192.168.1.161

You can see that to the backend server does not arrive the @lynzos.com part.

This is my perdition.conf file:

add_domain servername_lookup,1
authenticate_in ""
no_bind_banner ""
bind_address 0.0.0.0
connection_logging
connect_relog 300
client_server_specification ""
D @
d ""
F mail
g nobody
I IMAP4 IMAP4REV1
i ""
L 0
listen_port 110
login_disabled ""
lower_case servername_lookup
map_library /usr/lib/libperditiondb_gdbm.so
map_library_opt ""
no_daemon ""
n ""
O Hola
server_resp_line ""
protocol POP3
outgoing_port 110
pid_file /var/run/perdition/perdition.pid
pid_file /var/run/perdition.pop3/perdition.pop3.pid
pid_file /var/run/perdition.pop3s/perdition.pop3s.pid
pid_file /var/run/perdition.imap4/perdition.imap4.pid
pid_file /var/run/perdition.imap4s/perdition.imap4s.pid
t 1800
u nobody
username_from_database
q ""
query_key "\\U,+default@\\d"
ssl_mode ssl_all
ssl_ca_chain_file /etc/perdition/perdition.ca.pem
ssl_ca_file /etc/perdition/perdition.ca.pem
ssl_ca_path /etc/perdition/perdition.ca/
ssl_ca_accept_self_signed
ssl_cert_file /etc/perdition/perdition.crt.pem
ssl_cert_accept_self_signed
ssl_cert_accept_expired
ssl_cert_accept_not_yet_valid
ssl_cert_verify_depth 9
ssl_key_file /etc/perdition/perdition.key.pem
ssl_listen_ciphers "ALL:!ADH:RC4+RSA:+SSLv2:@STRENGTH"
ssl_outgoing_ciphers "ALL:!ADH:RC4+RSA:+SSLv2:@STRENGTH"
ssl_no_cert_verify
ssl_no_cn_verify

And this the relevant part of the popmap.re file:

(.*lynzos.com): 192.168.1.161