Basic Email Troubleshooting

This is a guide for basic email troubleshooting. Before reading this document, it is important to establish whether you have a connection to the Internet or not. Please refer to our other guides for details on this, but the easiest way to check is to see whether you can browse to an Internet web page or PING a reliable server in the outside world. This basic guide is meant for those who have proved they have a solid connection to the Internet but are having problems sending or receiving emails.

Quite a few problems with email can be client based. With so many different email clients out there, a good resource for troubleshooting individual client problems is:

We also have a document available for the retrieval and deciphering of email headers.


I cannot send or receive email

If you are able to connect to the Internet with no issues, but are unable to send or receive email then the problem is most likely to be one of two things: It could be is that the mail server is up and running fine but your connection route to the server is somehow failing, so first you should check that your connection to the server is up and functioning correctly. You can check this connection yourself, and it is a good idea to always run through this before logging a fault with anyone. This test will require that you know the name or IP address of your mail server.

This guide assumes you are using a Windows based system.

Open a command prompt by clicking the Windows menu icon and going to ‘Search’ and typing ‘cmd’– once the command prompt window is open, use the following command to try and connect to your mail server manually:

telnet 25

Where you replace with the address or name of your mail server.

If you receive a prompt back from the mail server with “Connected” or “220” then you are able to connect to your email server fine and chances are the server is responding and working ok. You can run further tests at this point using various commands, a handy little article on which is here:

To get out of the mail server, simply close the command prompt window or use the exit command.

The most common reason for email not working is that the email server you are using is either completely down or experiencing some serious problems. Your server will be hosted locally by your network / server staff or will be hosted off site by a third party company. In either instance, it is good idea to put in a call to them to see if there are any issues.

If you are able to connect to the server using the above test but you are unable to send or receive email from your machine, then your problem is most likely client based. It is best to check with your administrator that you have the settings correct within your email software.

If you run the telnet test and you receive an “Unable to connect” message or the request times out, then there is definitely some sort of network problem between your machine and the server, and you should contact your network administrator.

I can send email but I cannot receive

The first thing to always check in this situation is the MX records for your domain. If your email is hosted by a generic email firm such as or then you probably won’t need to do this, but certainly if your company hosts their own domain then this is the first place to check. Again, you may need to check with your server admin or email provider what the correct settings are supposed to be, but if you wish to check what the current live setting for your domain is then simply go to:

Another thing to check would be that your email box doesn’t have any forwarders setup to forward your inbound email to another address. This can either be done at a client level or with your provider, and is definitely worth checking.

The most effective way of troubleshooting this issue is to send a test email message from an email server that you or your provider has access to and you know is definitely fully operational. Send a test email message, noting down important information like time sent, the headers etc., then track the email from source to destination. So get your server admins to look at the test email on its outward journey to the point where it is definitely presented for delivery at your end. Either a bounce back message will be generated, which you will be able to analyse for clues, or you will be able to see on the receiving end what happened when the email was presented for delivery.

I can receive email but I cannot send

A good first thing to check would be that you are using authentication in the outgoing email settings within your client. Sometimes this step is skipped by email setup wizards or existing configurations can become corrupted. You will probably need to check with your email administrator what the authentication settings are, but if you know them yourself then this is always a good place to start before going elsewhere. Look out for this especially if you are receiving error messages or bounce back messages with the “5.7.1 Relaying denied” error.

Another thing to check would be to ensure that port 25 (SMTP) or port 587 (Authorised Submission) are not blocked on your network. Network administrators might have been making some changes and inadvertently blocked this port on your network, which would prevent outgoing email from working on the standard SMTP or Authorised Submission ports.

Chances are that you have already attempted to send emails which is why you have noticed this problem, but it is always a good idea to send a specific test message email that you can use for troubleshooting with your server administrator. Send a test message to another account that you also have access to and make a note of the time sent, headers of the email etc. Look out for any bounce back messages that may come back to you and show these to your administrator for analysis also. Refer to the below section for more information on bounce backs.

My recipients are (or I am) receiving bounce back emails saying the emails cannot be delivered

Whilst being very annoying, bounce back emails can contain a lot of clues as to what the problem is with the email path, and in a lot of cases provide the exact reason why the email was not able to be delivered. If you have received one yourself from a specific destination then don’t overlook it, and have a read through the information to see if you can spot anything useful. Similarly, if someone emailing you has received a bounce back and eliminated the problem being at their end, try and get hold of the message somehow so you can have a look.

The bounce back messages can be daunting and garbled at first site but scan through them for sentences and error messages. You might find something like “Recipient does not exist on that domain”, which would indicate you have typed the address wrong or you might read some sort of warning from an online spam policing service like Spamhaus or SpamCop which indicates that the sending server has picked up a bad reputation for sending spurious traffic or messages. This is really a job for the server administrators to take up with the spam policing service directly.

If you are finding it difficult to locate anything meaningful within the message then try looking for a string within the header that starts with “X-Spam Status”. This indicates that the email may have been picked up as spurious for having spam like elements to it. If what follows doesn’t make any sense, then trying googling for it or raising it with the anti-spam protection company that protects that particular recipient server.

More information on deciphering message headers can be found in our separate guide in How to get your email headers, and make sense of them

My email in either direction is significantly delayed and / or I am getting Disk Quota / Disk Full errors

This is a common error that comes up, especially on older mail servers that have not been updated for a while. Raise the issue with your server administrators, but before doing so make sure all of your email folders have been properly archived and you have gone through your Sent / Deleted items to clear out anything you don’t want any more. Also make sure you check your Junk folder.

Spam, so much spam!

Spam is an ever growing problem when it comes to email. 2014 statistics estimate that between roughly 65% – 75% of all email traffic is spam ( There is no way to prevent it infallibly but it is always a good idea to have measures in place to protect your email system from the influx that will inevitably occur. Most email providers come with a range of different anti-spam measures, so if your email is hosted online by a third party and you are having problems, discuss it with them. If you host your own email server then you should look into getting an additional protection service, especially if your company is more than a few employees. activereach Ltd offer the Mimecast product range which is widely regarded as the market leader in email protection. Please get in touch if you are interested or having problems.

One thing to be wary of is malicious emails or viruses penetrating your network that end up sending out masses of spurious emails or traffic. If you receive complaints that there is malicious email coming from your network then you should contact your network administrator immediately, and a full network clean up and audit is highly recommended.

activereach specialises in helping companies with business internet access as well as providing email security. Give us a call on 0845 625 9025 or contact us to find out more.