[SOLVED] timeout after DATA


Oct 22, 2017
Hi everyone, just installed and configured PMG 6.0, everything works good, except some clients can't connect to SMTP.
in mail.log i see only this kind of messages:

connect from client [ip]
timeout after DATA (0 bytes) from client [ip]
disconnect from client [ip] ehlo=1 mail=1 rcpt=1 data=0/1 commands=3/4


timeout after DATA (591 bytes) from client [ip]


lost connection after BDAT (1157 bytes) from client [ip]

What i tried:
-whitelist ip in fail2ban
-disable fail2ban completely
-whitelist ip in postscreen
-whitelist from SMTP checks in GUI

graylisting permanently turned off

On router i see the connect session to 25 port hanging untill timeout

I also tried to capture packets from particular client, but for me its non informative

SMTP 91 0.000087000 S: 354 End data with <CR><LF>.<CR><LF>
TCP 91 0.210234000 [TCP Retransmission] 25 → 56729 [PSH, ACK] Seq=262 Ack=179 Win=64256 Len=37
TCP 66 0.006393000 [TCP Previous segment not captured] 56729 → 25 [ACK] Seq=13979 Ack=299 Win=5760 Len=0 SLE=262 SRE=299
SMTP 12 299.881855000 S: 421 4.4.2 Proxmox-smtp Error: timeout exceeded

Google points to network misconfigurations like wrong mtu on host,vm,router etc...but first of all, we have more than 500 emails per day, from hundreds clients and only this particular experienced such troubles. But this is huge organisations like banks, so i don't believe that there can be such misconfigs too...

Thanks in advance for you suggestions!

pmgversion -V
proxmox-mailgateway: 6.0-1 (API: 6.0-6/b0c1ded4, running kernel: 5.0.21-2-pve)
pmg-api: 6.0-6
pmg-gui: 2.0-4
pve-kernel-5.0: 6.0-8
pve-kernel-helper: 6.0-8
pve-kernel-5.0.21-2-pve: 5.0.21-3
pve-kernel-5.0.21-1-pve: 5.0.21-1
libarchive-perl: 3.3.3-1
libjs-extjs: 6.0.1-10
libjs-framework7: 4.4.7-1
libpve-apiclient-perl: 3.0-2
libpve-common-perl: 6.0-4
libpve-http-server-perl: 3.0-2
libxdgmime-perl: 0.01-5
lvm2: 2.03.02-3
pmg-docs: 6.0-3
proxmox-mini-journalreader: 1.1-1
proxmox-spamassassin: 3.4.2-12
proxmox-widget-toolkit: 2.0-7
pve-firmware: 3.0-2
pve-xtermjs: 3.13.2-1
zfsutils-linux: 0.8.1-pve2
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