Understanding of Bounce  Email 

Below are the few  bounced example email with explanation.  This will help to under the reason behind the email bounce back.

1) Over quota error :--

=================

From: Mail Delivery System <MAILER-DAEMON@pop3.netcore.co.in>
 Date: Thu, Aug 9, 2012 at 1:23 PM
 Subject: Undelivered Mail Returned to Sender
 To: sender-ID@gmail.com
 
 
 This is the mail system at host  pop3.netcore.co.in.
 
 I'm sorry to have to inform you that your message could not
 be delivered to one or more recipients. It's attached below.
 
 For further assistance, please send mail to postmaster.
 
 If you do so, please include this problem report. You can
 delete your own text from the attached returned message.
 
                    The mail system
 
 <recipient-ID@pop2.netcore.co.in>: host  pop3.netcore.co.in[/var/lib/imap/socket/lmtp]
     said: 552 5.2.2 Over quota
     SESSIONID=<pop3.netcore.co.in-15031-1344498797-2> (in reply to RCPT TO
     command)
 
 
 Final-Recipient: rfc822; recipient-ID@pop2.example.com
 Original-Recipient: rfc822;recipient-ID@pop2.example.com
 Action: failed
 Status: 5.2.2
 Remote-MTA: dns; pop3.netcore.co.in
 Diagnostic-Code: smtp; 552 5.2.2 Over quota
     SESSIONID=<pop3.netcore.co.in-15031-1344498797-2>
 
Explanation :--  

------------------

The above bounce error means the mail quota of recipient's ID  i.e recipient-ID@example.com is exceed, Because of that the new emails are getting bounce back to sender ID sender-ID@gmail.com

####################################################################################################################################

2) Mailbox Unknown :-- 

    ================

From: Mail Delivery System [mailto:MAILER-DAEMON@netcore.co.in]
Sent: 27 September 2012 11:18 
To: sender-ID@gmail.com 

Subject: Undelivered Mail Returned to Sender

This is the mail system at host pop2.netcore.co.in.

I'm sorry to have to inform you that your message could not be delivered to
one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own
text from the attached returned message.

                   The mail system

<recipient-ID@pop2.netcore.co.in>: host
    pop2.netcore.co.in[/var/lib/imap/socket/lmtp] said: 550-Mailbox unknown.
    Either there is no mailbox associated with this 550-name or you do not
have
    authorization to see it. 550 5.1.1 User unknown (in reply to RCPT TO
    command)

Explanation :--   

------------------

The above error means that the recipient recipient-ID@pop2.netcore.co.in  is not having the mailbox on server and because that the email got bounce to sender sender-ID@gmail.com

########################################################################################################################################

3)  Delay warning Email  :-- 

    -------------------------------

 ####################################################################
# THIS IS A WARNING ONLY.  YOU DO NOT NEED TO RESEND YOUR MESSAGE. # 
####################################################################

Your message could not be delivered for more than 4 hour(s).
It will be retried until it is 3 day(s) old.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your 
own text from the attached returned message.

                  The mail system

<user1@gmail.com>: lost connection with 
mx1.gmail.com[101.101.101.101]
   while sending end of data -- message may be sent more than once

Explanation :-- 
-------------------

Note that its a warning email to sender.  This email means that the sender who send the email to user1@gmail.com is not delivered to Gmail.com ID. 
The Gmail.com MX server is not accepting the emails from netCORE SMTP server and  Because of that the email is still in queue for more that 4 hours. 
Such emails will keep in netCORE SMTP queue for 3 days. Between the period netCORE SMTP server will try to deliver the email to Gmail.com. 

########################################################################################################################################


4)  RBL ( Real time Blacklist )  IP lookup bounce email :-- 

From: Mail Delivery System [mailto:MAILER-DAEMON@localserver.netcore.co.in]
Sent: May 14, 2012 1:10 PM
To: Jayesh Shinde 
Subject: Undelivered Mail Returned to Sender

This is the mail system at host localserver.netcore.co.in.

I'm sorry to have to inform you that your message could not be delivered to
one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own
text from the attached returned message.

                   The mail system

<user1@gmail.com>: host mx1.gmail.com[160.83.90.10] said: 550 5.7.1
Rejected:
    202.162.229.136 listed at rbl-plus.mail-abuse.com (in reply to MAIL FROM
    command)

Explanation :-- 
-------------------

The above error means that the sender send the email to user1@gmail.com , but since sender SMTP server IP ( 202.162.229.136) is listed in RBL SPAM database
so mx1.gmail.com is not accepting the email and finally it got bounce with error "202.162.229.136 listed at rbl-plus.mail-abuse.com"


##########################################################################################################################################

5)    User unknown in virtual alias table 

      -----------------------------------------------------

This is the mail system at host smtp15.netcore.co.in.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

                   The mail system

<recipient-ID@pop2.netcore.co.in>: host 202.162.229.12[202.162.229.12] said: 550 5.1.1
    <recipient-ID@netcore.co.in>: Recipient address rejected: User unknown in
    virtual alias table (in reply to RCPT TO command)

Explanation :-- 
-------------------

Here sender-ID@gmail.com received above bounce message with error  "Recipient address rejected: User unknown in  virtual alias table"
Its means on server there is no email ID like recipient-ID@netcore.co.in
That is email is not correct.