Bounced Emails – Common Issues and What To Do

It happens to everyone once in a while – you send an email and it bounces back undeliverable.  You end up with a cryptic email which may have 30-40 lines of strange information in it, but what do you do to fix it?  Luckily the most common issues are easily resolved and the details of the issue are in the bounce message.

It’s just a matter of knowing what to look for.  Don’t let the long gibberish of the bounce email scare you!  Giving it a quick review will usually show the cause of the bounce:

Quota Exceeded

This is the most common issue and is usually the easiest to determine  as it generally appears near the top of the bounced email:

procmail: Quota exceeded while writing "/var/mail/johnsmith"

You can guess the issue here – the “johnsmith” email account is full.  If that’s your own account  or one of your users then you can login to webmail and delete old email from the inbox, or set the email program to delete old email when it downloads.  Either solution will clear up the issue, but setting the email program to delete old email will keep it clean automatically.

If you were sending to someone outside of your hosting account with LexiConn, then they would need to clean up their inbox with their mail provider.

User or Host Unknown

Very common, and usually easy to find in the bounce message:

550 5.1.1 <>... User unknown

If you see “User unknown” then the receiving email server may have a problem, or it could simply be a typo in the email address.  Check to make sure the email address is correct.  You may also see “Host unknown” which points to an issue with their mail server itself or just the domain name is wrong on the email address.  For example if you send an email to someone at but typed in you may see a “Host Unknown” bounce come back.

Large Emails

A less common issue, but usually easy to determine from the text of a bounce message is:

552 5.2.3 Message size exceeds fixed maximum 
message size (20000000)

The number at the end may vary in size, but the issue is still the same – the email was too large for the email server.  In this example the max size allowed is 20MB.  A normal text email would never reach this size, so there must have been a file attached.  The file itself may have been smaller than 20MB, but due to email encoding the total size of the message was over 20MB.

If you’re sending a variety of files in 1 email, the solution may be to simply split your attachments over 2-3 emails, assuming no single file is too large by itself.  Another option would be a forwarding service such as the one by HighTail below.  Their free option allows files up to 250MB to be sent.  The sender can upload a file to the website and it in turn emails a link  to the receiver to download the file:

The Dreaded Block List

This issue appears a large variety of ways, but the premise of the error is the same – your email was blocked due to the IP address being in a block list with either an ISP or a black list provider.  Here’s a sample of what it can look like in the bounce message:

550 OU-002 (BAY004-MC6F8) Unfortunately, messages from
 weren't sent. Please contact your Internet service provider since part of
 their network is on our block list. You can also refer your provider to

When you see an issue like this, the first thing to do is check to see if the IP address is your own.  To check your IP visit the following website:

They will show your IP address on the screen.  If it matches the one shown in the bounce message then your local IP is on the list.  If you have a business-class internet service you may be able to contact your ISP and have them work on getting the block cleared.  However if you’re emailing from home and have a regular residential internet service provided by someone like Comcast or Verizon there is usually no chance of ever getting the IP removed.

A better solution is to change your email program to send through your hosting account with us and not through your ISP.  When sending through your ISP your email goes out with your local IP and is then seen by all the email servers.  If you send email through your hosting account then your server’s IP with us is seen instead.

We have a section in our Knowledge Base here with articles for how to configure various email programs:

Basically you want to check to make sure your email program sends using “” with your email username and password.  A setting usually called “Outgoing Authentication” or “My outgoing server requires authentication” must be on which tells your email program to login when sending email.  This will allow your email to be sent through your hosting server.

Unfortunately not all email providers look at the sending IP correctly.  Even though you may have configured your program to send through us, some blacklists still look at the original source IP and block it.  If this is happening for you or if the IP in the bounce doesn’t match your local IP please forward us the bounce message and we will research it.

These are just a few of the many reasons emails may bounce.  Luckily the most common reasons are simple to resolve, but if you’re hosted with LexiConn and have not been able to find a cause for the bounce please don’t hesitate to forward it to us and we’ll take a look.  Be sure to include a copy of the bounced error as it will help us track down the cause, and (if it’s not already in the bounce email) including details such as the sending email address, the to email address, and the date/time the email was sent will help as well.

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