Why E-mails Bounce
In computer jargon, a bounced e-mail is one that never arrives in the recipient’s inbox and is sent back, or bounced back, to the sender with an error message that indicates to the sender that the e-mail was never successfully transmitted. But what happens when someone sends an e-mail out into cyberspace, and why do e-mails sometimes bounce back?
When a user attempts to send an e-mail, he is telling his e-mail system to look for the domain of the recipient (for example, webopedia.com) and the domain’s mail server. Once the e-mail system makes contact with the recipient’s mail server, the mail server looks at the message to determine if it will let the message pass through the server. If the recipient’s server has predetermined that it is not accepting e-mails from the sender’s address (for example, if it has blocked the address for anti-spamming purposes), the server will reject the message and it will subsequently bounce back to the sender.
The message will also bounce back to the server if the mail server on the recipient’s end is busy and cannot handle the request at that time. When an e-mail is returned to the sender without being accepted by the recipient’s mail server, this is called a hard bounce. Once the e-mail has been accepted by the recipient’s mail server there are still ways for the message to be rejected.
The mail server has to determine if the recipient (for example, webmaster@webopedia.com) actually exists within its system and if that recipient is allowed to accept e-mails. If the recipient’s address does not exist on the mail server, then the message will be rejected because there is no one to deliver the message to. If the sender misspells the recipient’s address (for example, webmaster@webopedia.com) then the system will recognize this as a nonexistent address and bounce the message back.
If the recipient exists but does not have enough disk space to accept the message (i.e., if his e-mail application is filled to storage capacity) then the message will bounce back to the sender. Some mail systems predetermine a maximum message size that it will accept and will automatically bounce the message if it exceeds that size and some mail systems predetermine a maximum amount of disk space the user is allowed to occupy on the server. When an e-mail is returned to the sender after it has already been accepted by the recipient’s mail server, this is called a soft bounce. Some mail servers are programmed to accept incoming e-mails and store them for further analysis without initially checking to determine if the recipient exists or is even capable of receiving the message. Occasionally, a network failure at the sender or recipient end will cause an e-mail to bounce back to the sender. Typically, a bounced e-mail returns to the sender with an explanation of why the message bounced.
Checklist:
E-mails bounced back basically due to error. Error maybe on the sender’s side or on the recipient’s side.
ITEM A:
Possible error on sender’s side:
1.) Sender misspells the recipient’s address making it a nonexistent address. Please double check the spelling of the email address. E.g. myemail@mydomain.com is different from myemail@sigmaksa.net.
2.) Sender mail client (MS Outlook, Outlook Express, Webmail) encounter an error. This one basically does not send your email, it remains on your outbox until the error is resolve. In most cases a warning or error message appear. Please read the error message carefully because that information alone you can check what cause the problem.
3.) Sender attempts to send a file that exceeds email server’s allowable file size attachment. Most mail servers like yahoo.com, gmail, etc. allows only up to 10MB file attachment, we suggest that you send your email by batch because large file attachment will cause our email server & the recipient email server to respond slowly. You can also verify to your contact how much is the maximum allowed email attachment their server can receive.
4.) Sender’s mail server or Internet Service Provider (ISP) encounters an error. E-mail remains on sender’s outbox until the error is resolve. In most cases a warning or error message appears.
5.) Sender sends an e-mail that has an attachment not allowed by sender’s mail server to be delivered. Most email server allows .gif, .doc. .xls, .ppt, .pps, .pdf, .jpg, .txt, .zip, .bmp, etc. to be received.
6.) You are trying to send an email with attachment and the attach file contains special characters such as “ & + # \ / : * ? ” ‘ < > | ! . “ on their file name. Please avoid using this characters when saving your files. (Please read source # 1 below regarding simple file naming rules.)
Ex.
Bad file name = My.Document.File.doc
Good/Acceptable file name = My_Document_File.doc
6.) You are trying to send an email with a subject that contains special characters such as “ & + # \ / * ? ” ‘ < > | ! . “ . If possible keep your email subject simple to avoid risk of having problem later on, this rule also applies on file naming convention of your documents. Keep it simple.
7.) Network or Internet failure on sender’s end.
ITEM B:
Possible error on recipient’s side:
1.) The recipient’s email server or ISP encounters an error. A warning or error message will be send to sender from recipient’s mail server. (e.g. recipient’s mail server does not have enough disk space to accept messages or the recipient’s mail server is busy and cannot handle the request at that time)
2.) The recipient’s email server or ISP blocks e-mail for anti-spamming purposes. A warning or error message will be send to sender from recipient’s mail server stating that the mail has been blocked.
3.) Recipient’s email server does not allow certain filename or file type attachment to be received. (e.g. “.” on filename please see Item A #6)
4.) The recipient’s mail server or ISP has a limit on the file attachment size. Some mail systems predetermine a maximum message size that it will accept and will automatically bounce the message if it exceeds that size. (e.g. Yahoo allows on 10MB, please see Item A #3)
Conclusion:
A bounced e-mail has an explanation of why the message bounced, please check the possible reasons or forward your bouncing email message to help@mydomain.com to analyze the error message for you. You can forward questions regarding e-mail bounce at help@mydomain.com.
Sample error message: (Account disabled)
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Message from yahoo.com.
Unable to deliver message to the following address(es).
<emailaddress@yahoo.com>:
Sorry your message to emailaddress@yahoo.com cannot be delivered. This account has been disabled or discontinued [#102].
— Original message follows.
The original message is over 5K. Message truncated.
X-Originating-IP: [123.456.789.012]
Return-Path: <help@mydomain.com>
Authentication-Results: mta230.mail.re2.yahoo.com from=mydomain.com; domainkeys=neutral (nosig)
Received: from 123.456.789.012 (EHLO mail.mydomain.com) (123.456.789.012)
by mta230.mail.re2.yahoo.com with SMTP; Fri, 19 Oct 2007 04:13:09 -0700
Received: from dapcoo8 ([123.456.789.012])
by mail.mydomain.com (8.13.5/8.13.5) with ESMTP id l9JACHw1002331
for <uap@dap.edu.ph>; Fri, 19 Oct 2007 18:12:17 +0800
From: ” help@mydomain.com” <help@mydomain.com>
3
To: < emailaddress@yahoo.com >
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Sample error message: (Recipient Mailbox is full)
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This is the Sendmail (8.12.11/8.12.11) program at host mail.mydomain.com.
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 Sendmail (8.12.11/8.12.11) program
<user1@mydomain.com>: maildir delivery failed: Sorry, the user’s mailbox has overdrawn his diskspace quota, please try again later.
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Source 1:
http://www.worldstart.com/tips/tips.php/3286
http://classes.yale.edu/help/itg/classes/Fundamentals/File_Names.htm
Source 2:
http://www.webopedia.com/DidYouKnow/Internet/2002/BouncedEmail.asp
Other related articles:
http://www.qksoft.com/qk-smtp-server/why-email-bounce.html