Email bounce Message
From Novara Support Knowledgebase
An error message from email delivery subsystem (mailer-daemon) indicates that there was a problem in delivering your message to its destination. When you receive an error from the mail system, your message will be returned to you along with an outline of the mail delivery problem.
This document will help you become more familiar with the format and content of error messages so you can identify delivery problems and possibly correct the situation.
Contents |
Temporary Problems likely to be fixed soon
- 552 MAILBOX FULL
The most common user problem is a full mailbox. Most systems have a limit on how much email is allow to reside on the server for each user, and once that limit is reached, there is no room to accept new incoming mail. The following are all examples of bounce messages caused by a full mailbox:
<user@test.com>: User is over the quota. You can try again later.
<user@example.net>: host in7.explae.net said: 552 <user@example.net>... Mailbox is full
procmail: Mailbox limit exceeded while appending message 550 <user@eg.net.do>... Can't create output
<user@ui.com>: host mail9.ui.com said: 552 Requested mail action aborted: exceeded storage allocation
This error will stop as soon as the recipient makes additional room in their mailbox (usually by removing old messages from the server), so you should probably resend your message a little later. However, especially with free accounts, this message could actually mean the user no longer checks the account; a good rule of thumb is if you continue to receive this error for more than two weeks, it is likely that the account is no longer in use.
- 552 MESSAGE EXCEEDS MAXIMUM FIXED SIZE
<user1@test.com>: host mx-rr.test.com said:
552 Message size exceeds fixed maximum message size (5000000)
<user@example.net>: host mx2.mail.example.net said:
552 message size exceeds maximum message size
<user@ui.com>: host mx01.mail.ui.com said:
552 Message size exceeds fixed maximum message size: 5242880 bytes
These errors mean that the size of the message, including all headers, text and attachments, exceeds the domain's maximum per-message size limit - essentially, that your email is too big to be accepted. You should try to reduce the size of the message, or try to split the email into smaller parts and resend it.
Other types of errors that should be quickly fixed can be caused by users misconfiguring their own email accounts. For instance:
- 554 Too many hops
Improper forwarding causing mail loop:
>554 Too many hops 27 (25 max): from <user@firstdomain.com> >via mail.firstdomain.com, to <sameuser@seconddomain.com>
In general, a "too many hops" error indicates a mail loop: the user has two accounts, forwarding to each other, which creates an endless loop. A message sent an Test.com account is forwarded to another mailbox; if that account is set to forward to Test.com, then a mail loop is created: mail goes from Test.com to the mailbox back to Test.com back to the mailbox, until the loop is ascertained and the message returned to its sender.
- Connection Timed Out / Connection Refused
<user@166.131.9.213>: connect to 166.131.9.213: Connection timed out
A "connection refused," or "connection timed out" message usually results from high volumes of mail being processed at the time your message was received. This could be due to the server receiving more mail then it is used to, a external attack on a domain (such as a mailbomb) or an internal setup problem, causing the domain's mail servers to refuse connections or cut connections before a message is fully sent. Mail exchangers are set up to only accept as much mail as they can handle, so when problem is resolved, you will be able to send your mail without problem.
- Relay Access Denied
Another domain error that can be due to either the sender's or recipient's domain is a relay access denied error:
<recipient@udom.ie> host wormwood.test.ie said:
554 <recipient@udom.ie>: Recipient Address rejected:
Relay access denied
This error indicates that, somehow, a message intended for a udom.ie address found its way to wormwood.test.ie mail server, and since this server doesn't accept mail for udom.ie, the message was rejected. It is quite rare, actually, to reach a completely incorrect mail server when sending email to a domain, so if you receive this message, the problem is usually a misconfiguration error with the receiving domain (for example, if you receive notice that mail sent to a test.ie user was rejected by a test.ie mail server with this "Recipient Address rejected," error, this could indicate a problem with test.ie mail servers, since test.ie mail servers obviously should accept email for test.ie users. Or, it could indicate a problem where the sender's system isn't looking the mail server up correctly).
Another reason for receiving this error is the possibility that a domain has recently changed hosts, and while the change has taken place, the new domain record has not yet propagated fully, and your message reached the old hosting company which no longer accepts mail for the leaving domain. If you receive this error, try resending your message twenty-four hours later.
- 550 SENDER DOMAIN NOT FOUND IN DNS
- 550 REQUESTED ACTION NOT TAKEN: DNS FAILURE
These errors indicate that there are DNS resolution problems somewhere between their domain and us. This usually means that Novara is unable to resolve their domain name in DNS before accepting that mail for delivery. This might be because their DNS servers are offline (in which case try again later, or give us an email so we can troubleshoot for you), or you made a typo. Doublecheck to ensure that you haven't misspelt the domain name.
Permanent Problems
Example 1:
> Hi. This is the qmail-send program at mail.shanghaiguide.com.cn. > I'm afraid I wasn't able to deliver your message to the following > addresses. > This is a permanent error; I've given up. Sorry it didn't work out. > > <richard@test.com>: > Sorry, I couldn't find any host named test.com. (#5.1.2)
The important details are here - > <richard@test.com>: > Sorry, I couldn't find any host named test.com. (#5.1.2) What it is saying, is that it couldn't find any domain name called test.com Usually you'll get this if you have made a spelling mistake in the domain name.
Example 2:
From: MAILER-DAEMON@eg.com (Mail Delivery System)
Subject: Undelivered Mail Returned to Sender
To: XXXX
Auto-Submitted: auto-replied
This is the mail system at host sbh2.eg.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 mail system
<paul@egdt.com>: User unknown in virtual alias table
The important details are here - <paul@egdt.com>: User unknown in virtual alias table What its saying, is that the email address is not known at that server. This can be for a number of reasons, such as:
- that email address is no longer valid (eg the person has moved companies)
- you made a spelling mistake in the email address.
- 550 MAILBOX NOT FOUND
This error indicates that the address no longer exists or the email address is mis-spelled.
Anti-Spam Bounces
System administrators frequently set up their systems to refuse mail from spammers, but since no spam filtering system is perfect, your message may have been caught in the spam block. Some of the most common:
Example 1:
<user@sitcom.co.il>: host ntserver.sitcom.co.il refused to talk to me: 550 Permission denied
The above errors mean that your provider's domain name (or specifically, your email address) is explicitly listed as a known spammer on a blacklist. This may be based on an external service that provides blacklists of known spammers to ISPs, or the administrator may have placed a block based on a large volume of mail coming from your domain. Most of the time, your email provider will need to contact the system administrator to have the block removed, so you should contact your provider immediately.
Or you may get following Spam blocks bounces
451: Blocked please visit http://ORDB.org/lookup/?host=X.X.X
or
451 Blocked - see http://www.spamcop.net/bl.shtml?X.X.X
or
451 Mail from X.X.X/24 refused, see http://anti-spam.org.cn/services/rblquery.php?IP=X.X.X
The message in question was blocked because it came from a domain or IP address that is currently listed with one of our Spam filters. These filters are utilized to help prevent excessive spamming to our email providers. If your domain or IP address is listed with any of the Spam filters we currently use, your message will not be delivered.
If you believe that you have been unfairly added to any or all of these particular lists, please contact the website in question:
• Ordb (relays.ordb.org) • Spamcop (bl.spamcop.net) • Osirusoft (socks.relays.osirusoft.com) • Wirehub (blackholes.wirehub.net) • Spamhaus (www.spamhaus.org) • AntiSpam (www.anti-spam.org.cn)
Example 2:
Hi. This is the qmail-send program at mail.example.com. I'm afraid I wasn't able to deliver your message to the following addresses. This is a permanent error; I've given up. Sorry it didn't work out. <really-sorry@test.biz>: 172.31.0.5 does not like recipient. Remote host said: 550 "Unknown User" Giving up on 172.31.0.5.
The important details are here - Remote host said: 550 "Unknown User" In this case its an evil spammer trying to setup an account, and providing a fake address.
Example 3:
<recipient@pobox.com>:host cali-1.pobox.com said: 554
<user@fake_domain.com>: Sender Address Rejected: domain not found
This is an anti-spam bounce. Notice the "Sender Address Rejected"; this means that the problem is actually with the Sender's email address - specifically, that the domain used in the sender's email address was not a valid domain. When a mail server receives an email for one of its users, the server checks to ensure that the sender's domain is a real domain - if the domain name does not resolve, the message is rejected with the "Sender Address Rejected" error. This is an anti-spam error in that it prevents mail servers from accepting spam where the domain is completely fake, meaning the message could not really have originated there.
Example 4:
The other type of "554 Relay Access Denied" error is a problem with the sender using the wrong mail server to send their message:
<sender@pobox.com> host smtp-gw-4.msn.com said:
554 <sender@pobox.com>: Sender Address rejected:
Relay access denied
Essentially, this error message is similar to a Recipient Address rejected, in that the server reporting the error does not like the domain name; however, in this case, the problem is that the outgoing email server did not like the domain of the sender's email address (as opposed to the above Recipient errors, where the incoming mail server does not like the recipient's domain).
What this error generally indicates is that the outgoing server you're using (usually the one assigned to you by your ISP) will not accept email with the From: address you've used on the email. For example, domains such as BellAtlantic.com, GTE.net, and Verizon.com do not allow users to send email their outgoing mail server if the "From" email address used on the message is not the one assigned by them (e.g. you can't send out mail that uses your Pobox address as the From: header via their mail servers). Many ISPs have begun to enforce these restrictions to prevent spammers from using the ISP's access and SMTP server to send spam. To remedy this error, you will need to use the email address assigned to you by the provider as the From: address on outgoing email.
Other Bounce Messages
Example 1:
550: name.mail.domain.net[10.x.xxx.xx]: Client host rejected: More than 20 concurrent connections per subnet
It appears that the mail servers that were responsible for delivering the message to us were temporarily blocked due to a high number of concurrent connections. This type of abuse is usually indicative of a "spammer" trying to send unsolicited commercial emails. Therefore, the message was blocked along with all other messages from that mail server at that time. However, it is likely that the block was subsequently removed.
Example 2:
554: unknown[10.xxx.xxx.xx]: Client host rejected: Access denied 554: Sender address rejected: Access denied
Your message is being blocked because it either had characteristics similar to "spam" (unsolicited commercial email), or you're sending your message from an email provider who has been identified as having allowed spam to be generated from their facilities.
For example, it is possible that the subject line of the message in question may have been identified by mail servers as unsolicited commercial mail (AKA: Spam) and thus was returned. You can retry sending your message with a different subject line.
However, if your email provider has been added to a block list, your email message to the sending email address will continue to be rejected or a bounced message will continue to be generated. If this is the case, please contact your email provider as they will need to look into the block.
Example 3:
554: Client host rejected: cannot find your hostname, [10.xxx.xx.xxx]; from=xxxxx@hotmail.com 554: Relay access denied; from=email@domain.com to=email@anotherdomain.com
This error means that the person sending the email was not authorized to use the email server (SMTP) server to send email. They should contact their ISP or email provider.
Example 4:
reject: header Subject: (Email Subject Line Here)
This subject line is on our "black list" of subject lines, or is on the black list of one of the spam filter lists we use to lessen the amount of Spam our users receive. You should have the sender of this email contact us if they have questions, or ask them, to change the subject line, which unfortunately appears to have been used as the subject of a "spam" message at some time.
Example 5:
554: Service unavailable; [10.xxx.xx.xxx] blocked using relays.ordb.org, reason: This mail was handled by an open relay - please visit http://ORDB.org/lookup/?host=10.X.X.X
The message in question was blocked because it came from a domain or IP address that is currently listed with one of our Spam filters. These filters are utilized to help prevent excessive spamming to our email providers. If your domain or IP address is listed with any of the four Spam filters we currently use, your message will not be delivered.
If you believe that you have been unfairly added to any or all of these particular lists, please contact the website in question: Ordb (relays.ordb.org) Spamcop (bl.spamcop.net) Osirusoft (socks.relays.osirusoft.com) Wirehub (blackholes.wirehub.net) Spamhaus
Example 6:
554: Relay access denied; from= to= - reject: header Subject: (Email Subject Line) Remote host said: 554 Service unavailable; [XXX.XXX.XXX.XXX] blocked using blackholes.test.com
Where test.com have recently received a large number of abuse complaints regarding your account (and/or your email provider). As a result, test.com have bounced your email message back to you.
This means your IP number (represented above by XXX.XXX.XXX.XXX) has been blocked due to spamming activity by you, or someone using the same IP address or IP address range from your email provider. You may wish to let your email provider know of the situation. While this blocks are usually temporary, if we see repeated activity from this IP address or IP address range, it may be permanently blocked from sending email to test.com mail system
Decoding Bounce Messages: What To Do
A few simple recommendations for dealing with bounce messages, especially if they are unfamiliar bounces:
Do:
- Contact the person you're trying to mail by other means. They may not know they are bouncing mail.
- Keep the bounce message. It can help tech support staff solve the problem quickly. It also (usually) contains the original message, which you may need to resend after the problem is fixed.
- Try to send yourself a test message if someone tells you your account is bouncing mail. If possible, use an account from a different domain than the account you are trying to test.
Don't:
- Try to respond to the bounce message; it will rarely yield any results.
- Continue trying to mail users after 2 or 3 tries (for permanent errors) or a week (for temporary errors). (note: This is doubly true if you run a mailing list. Remove subscribers when they begin bouncing with permanent failures. They have probably already resubscribed with a new address, and didn't remove their old address.)
- Assume that just because you can send a message to yourself that everyone else can. Mail that does not leave your domain is usually handled differently than mail that originates externally.
