That is exactly what it says, a service time out when you are sending
email. You are probably on a very active server, a very bad/slow or busy
connection.
How busy is your server? Do you have some network stats?
On 10/11/2016 21:54, Rob A wrote:
We are having issues sending emails with attachments over ~2 MB to some
recipients. In the situations were we have an error, the remote server
responds with "421 4.4.2 service timed out. (in reply to end of DATA
command)".
We are not having these issues with all recipients, but there are many
recipients to which we cannot send emails with attachments over ~2 MB. We
can send emails with larger attachments to some recipients (gmail.com and
yahoo.com addresses in particular) with no issues.
Any help is appreciated.
- Rob
# Output of postconf -n
bounce_queue_lifetime = 2h
config_directory = /etc/postfix
debug_peer_list =
local_recipient_maps =
local_transport = error:local mail delivery is disabled
maximal_backoff_time = 20m
maximal_queue_lifetime = 2h
message_size_limit = 104857600
minimal_backoff_time = 10m
mydestination =
mydomain = myhome.com
myhostname = mail.$myorigin
mynetworks = 127.0.0.0/8 10.10.10.0/24 10.10.100.0/24
myorigin = $mydomain
queue_run_delay = 10m
relay_domains = $mydomain myhome.com
relay_recipient_maps = hash:/etc/postfix/relay_recipients
smtpd_delay_reject = yes
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks, reject_non_fqdn_helo_hostname,
reject_invalid_helo_hostname, check_helo_access
pcre:/etc/postfix/helo_access, permit
smtpd_recipient_restrictions = reject_unauth_pipelining,
reject_non_fqdn_recipient, permit_mynetworks, check_client_access
hash:/etc/postfix/recipient_whitelist, check_recipient_access
hash:/etc/postfix/recipient_blacklist, reject_unauth_destination,
reject_rbl_client b.barracudacentral.org, reject_rbl_client
zen.spamhaus.org, reject_rbl_client bl.spamcop.net, reject_rbl_client
zombie.dnsbl.sorbs.net, reject_rbl_client nomail.rhsbl.sorbs.net,
reject_rbl_client bl.blocklist.de, permit
smtpd_sender_restrictions = check_sender_access
pcre:/etc/postfix/sender_blacklist, reject_non_fqdn_sender,
reject_unknown_sender_domain, permit
transport_maps = hash:/etc/postfix/transport
virtual_alias_maps = hash:/etc/postfix/virtual
# Here is the output from tcpdump
No. Time SourceDestination
Protocol Length Info
1 2016-11-08 17:32:22.658734 10.10.10.123 DDD.222.3.44
TCP 70 47372 > smtp [SYN] Seq=0 Win=29200 Len=0 MSS=1460
SACK_PERM=1 TSval=2863432 TSecr=0
Frame 1: 70 bytes on wire (560 bits), 70 bytes captured (560 bits)
Ethernet II, Src: RealtekU_bd:b1:11 (52:54:00:bd:b1:11), Dst:
LexCompu_0b:09:35 (4c:02:89:0b:09:35)
Internet Protocol Version 4, Src: 10.10.10.123 (10.10.10.123), Dst:
DDD.222.3.44 (DDD.222.3.44)
Transmission Control Protocol, Src Port: 47372 (47372), Dst Port: smtp (25),
Seq: 0, Len: 0
No. Time SourceDestination
Protocol Length Info
2 2016-11-08 17:32:22.697919 DDD.222.3.44 10.10.10.123
TCP 70 smtp > 47372 [SYN, ACK] Seq=0 Ack=1 Win=14480 Len=0 MSS=1460
SACK_PERM=1 TSval=989115275 TSecr=2863432
Frame 2: 70 bytes on wire (560 bits), 70 bytes captured (560 bits)
Ethernet II, Src: Dell_53:eb:0c (00:13:72:53:eb:0c), Dst: RealtekU_bd:b1:11
(52:54:00:bd:b1:11)
Internet Protocol Version 4, Src: DDD.222.3.44 (DDD.222.3.44), Dst:
10.10.10.123 (10.10.10.123)
Transmission Control Protocol, Src Port: smtp (25), Dst Port: 47372 (47372),
Seq: 0, Ack: 1, Len: 0
No. Time SourceDestination
Protocol Length Info
3 2016-11-08 17:32:22.698002 10.10.10.123 DDD.222.3.44
TCP 66 47372 > smtp [ACK] Seq=1 Ack=1 Win=29200 Len=0 TSval=2863442
TSecr=989115275
Frame 3: 66 bytes on wire (528 bits), 66 bytes captured (528 bits)
Ethernet II, Src: RealtekU_bd:b1:11 (52:54:00:bd:b1:11), Dst:
LexCompu_0b:09:35 (4c:02:89:0b:09:35)
Internet Protocol Version 4, Src: 10.10.10.123 (10.10.10.123), Dst:
DDD.222.3.44 (DDD.222.3.44)
Transmission Control Protocol, Src Port: 47372 (47372), Dst Port: smtp (25),
Seq: 1, Ack: 1, Len: 0
No. Time SourceDestination
Protocol Length Info
4 2016-11-08 17:32:22.750683 DDD.222.3.44 10.10.10.123
SMTP 167S: 220 AAA.mailsrvr.com ESMTP - VA Code Section 18.2-152.3:1
forbids sending spam through this system
Frame 4: 167 bytes on wire (1336 bits), 167 bytes captured (1336 bits)
Ethernet II, Src: Dell_53:eb:0c (00:13:72:53:eb:0c), Dst: RealtekU_bd:b1:11
(52:54:00:bd:b1:11)
Internet Protocol Version 4, Src: DDD.222.3.44 (DDD.222.3.44), Dst:
10.10.10.123 (10.10.10.123)
Transmission Control Protocol, Src Port: smtp (25), Dst Port: 47372 (47372),
Seq: 1, Ack: 1, Len: 101
Simple Mail Transfer Protocol
No. Time SourceDestination
Protocol Length Info
5 2016-11-08 17:32:22.750735 10.10.10.123