Email sending error because of too many connections

There were many reason of email sending error. One of them is because of too many connections to the server. This is the sample MDaemon email server logs of sending mail failure because of too many connections to the mail server.

Sender user is: user@mycompany.com
Recipient user is: theuser@telkom.net

In this log there is line:

Fri 2010-03-12 07:41:33: <-- 421 #4.4.5 Too many connections to this host Fri 2010-03-12 07:41:33: --> QUIT
Fri 2010-03-12 07:41:33: Socket connection closed by the other side (how rude!)

This mean the recipient mail server could not receive email from user@mycompany.com because in the same time the server receipt too many connection (may be from other email server) that could not be handled.

MDaemon server (Sender user mail server) will automatically resend the mail from user@mycompany.com to theuser@telkom.net next time depend on the setting of MDaemon mail server.

Fri 2010-03-12 07:41:33: Session 8894; child 10
Fri 2010-03-12 07:41:31: Parsing Message
Fri 2010-03-12 07:41:31: From: user@mycompany.com
Fri 2010-03-12 07:41:31: To: theuser@telkom.net
Fri 2010-03-12 07:41:31: Subject: Kelebihan Pengobatan
Fri 2010-03-12 07:41:31: Message-ID:
Fri 2010-03-12 07:41:31: MX-record resolution of [telkom.net] in progress (DNS Server: 202.152.0.2)...
Fri 2010-03-12 07:41:31: * P=011 S=000 D=telkom.net TTL=(0) MX=[mx2.mail.plasa.com] {222.124.18.72}
Fri 2010-03-12 07:41:31: * P=011 S=001 D=telkom.net TTL=(0) MX=[mx1.mail.plasa.com] {222.124.18.71}
Fri 2010-03-12 07:41:31: Attempting MX: P=011 S=000 D=telkom.net TTL=(0) MX=[mx2.mail.plasa.com] {222.124.18.72}
Fri 2010-03-12 07:41:31: Attempting SMTP connection to [222.124.18.72 : 25]
Fri 2010-03-12 07:41:31: Waiting for connection...
Fri 2010-03-12 07:41:32: Connection established (192.168.0.25 : 2790 -> 222.124.18.72 : 25)
Fri 2010-03-12 07:41:32: Waiting for protocol initiation...
Fri 2010-03-12 07:41:32: <-- 421 #4.4.5 Too many connections to this host. Fri 2010-03-12 07:41:32: --> QUIT
Fri 2010-03-12 07:41:32: Attempting MX: P=011 S=001 D=telkom.net TTL=(0) MX=[mx1.mail.plasa.com] {222.124.18.71}
Fri 2010-03-12 07:41:32: Attempting SMTP connection to [222.124.18.71 : 25]
Fri 2010-03-12 07:41:32: Waiting for connection...
Fri 2010-03-12 07:41:32: Connection established (192.168.0.25 : 2798 -> 222.124.18.71 : 25)
Fri 2010-03-12 07:41:32: Waiting for protocol initiation...
Fri 2010-03-12 07:41:33: <-- 421 #4.4.5 Too many connections to this host. Fri 2010-03-12 07:41:33: --> QUIT
Fri 2010-03-12 07:41:33: Socket connection closed by the other side (how rude!)
Fri 2010-03-12 07:41:33: This message is 1 days old; it has 4 days left to get delivered
Fri 2010-03-12 07:41:33: SMTP session terminated (Bytes in/out: 94/12)

Mail Transient Non-Fatal Delivery Errors

If you sent mail to you colleague and you receipt delivery error message like this:

The attached message had transient non-fatal delivery errors

THIS IS A WARNING MESSAGE ONLY - YOU DO NOT NEED TO RESEND YOUR MESSAGE!

This server is configured to automatically retry delivery at configured intervals. Subsequent attempts to deliver this message are pending.

Failed address: user@domain.com

--- Session Transcript ---
Fri 2009-10-16 17:33:35: Parsing Message
Fri 2009-10-16 17:33:35: From: sender@domain.co.id
Fri 2009-10-16 17:33:35: To: user@domain.com
Fri 2009-10-16 17:33:35: Subject: FW: Rencana sewa utk Factory Fri 2009-10-16 17:33:35: Message-ID: 07bb61b141d34c77aab6357e0cd846b2@mydomain.com
Fri 2009-10-16 17:33:35: MX-record resolution of [domain.com] in progress (DNS Server: 202.152.0.2)...
Fri 2009-10-16 17:33:45: * Error: 10 second wait for DNS response exceeded (attempt 1 of 3)
Fri 2009-10-16 17:33:45: MX-record resolution of [domain.com] in progress (DNS Server: 202.152.5.36)...
Fri 2009-10-16 17:33:55: * Error: 10 second wait for DNS response exceeded (attempt 2 of 3)
Fri 2009-10-16 17:33:55: MX-record resolution of [domain.com] in progress (DNS Server: 202.152.0.2)...
Fri 2009-10-16 17:34:06: * Error: 10 second wait for DNS response exceeded (attempt 3 of 3)
Fri 2009-10-16 17:34:06: Attempting SMTP connection to [domain.com : 25]
Fri 2009-10-16 17:34:06: A-record resolution of [domain.com] in progress (DNS Server: 202.152.0.2)...
Fri 2009-10-16 17:34:15: * Error: 10 second wait for DNS response exceeded (attempt 1 of 3)
Fri 2009-10-16 17:34:15: Attempting SMTP connection to [domain.com : 25]
Fri 2009-10-16 17:34:15: A-record resolution of [domain.com] in progress (DNS Server: 202.152.5.36)...
Fri 2009-10-16 17:34:15: Packet from DNS server contained an outdated response
Fri 2009-10-16 17:34:25: * Error: 10 second wait for DNS response exceeded (attempt 2 of 3)
Fri 2009-10-16 17:34:25: Attempting SMTP connection to [domain.com : 25]
Fri 2009-10-16 17:34:25: A-record resolution of [domain.com] in progress (DNS Server: 202.152.0.2)...
Fri 2009-10-16 17:34:35: * Error: 10 second wait for DNS response exceeded (attempt 3 of 3)
Fri 2009-10-16 17:34:35: This message is 60 minutes old; it has 0 minutes left in this queue
Fri 2009-10-16 17:34:35: Primary queue lifetime exceeded; message placed in retry queue
--- End Transcript ---
: Message contains [1] file attachments

This mean email from you to your colleague has not sent yet but your mail server will try to resend this email until the time of mail server at configured intervals. You don’t have to resend your message.