Having spent many years dealing with websites and the design thereof, I have been using the Plesk Control Panel for managing my websites for most of that time and I have always found it to be very easy to perform all of the required maintenance tasks.

I have recently taken to using the IMAP service for the management of my mailboxes and also recommending it to others as a much easier way to manage your mail and keeping it tidy and uniform, particularily if you are managing your email with multiple clients, such as mobile, webmail and desktop, which lets face it, most of us are these days.

Why is it easier? Well the answer is that if you manage your mail via POP3 as many people do and have done for many years then you will find that you are having to duplicate your mail management over multiple clients, because any management that you do on your mobile email will not be replicated to your desktop or webmail clients. Even the simplest functions such as emails that you have read are not replicated to the other clients and this can be very frustrating…

The solution…use IMAP instead of POP3

IMAP will not only allow you to read emails and manage the fact that they have been read by sharing those details across all the clients that you use to read and reply to your emails, but it will let you do much more than that. It will allow you to manage your emails using folders much like some of you will be used to if you are using corporate solutions such as Microsoft Exchange or Lotus Notes.

You will have to use a suitable client such as Microsoft Outlook to create your desired folder structure, or you can perhaps use the Webmail client that your ISP has available.

Unfortunately, most mobile solutions do not allow for the creation of folders, I know for instance that the iPhone will allow you to manage your mail and place it into any folders that you have, but it will not allow for the creation of NEW folders which is a shame. I am not sure if the Android mail application will allow the creation of IMAP folders, but hopefully someone can set me straight on that point?

Another important factor to consider is ensuring that your ISP has correctly configured the IMAP setting on their servers, because unfortunately the default settings are usually insufficient for dealing with the wide variety of mobile and desktop clients that people are using these days.

The most common issue that you might see is something along the lines of…

“Unable to connect to server mail.domain.com; Check username and password are entered correctly”

or something similar to this.

Yes, these errors will occur even after you have been using the mailbox quite happily for quite some time, and they will happen out of the blue, perhaps even when you have just been successfully reading your emails.

Naturally you will check your username and password and find that they are correct and you will continue to get the error and become very frustrated.

I can tell you now that here is not a problem with your username or your password, the problem lies with the configuration of your IMAP server

So IMAP is not all plain sailing and yes there are some drawbacks, but once you are aware of what those are you can overcome them relatively easily.

I am happy to share the details of how this can be acheived on a PLESK controlled server and I would imagine that the process is very similar for many other linux based web servers.

Plesk utilises the Courier Mail Server for the provision of its IMAP and POP3 mail services and although the “out of the box” POP3 setting are perfectly acceptable for dealing with most if not all requirements, the IMAP settings although workable will certainly give some minor irritating problems that can be easily avoided.

Plesk comes with a maximum permissable number of connections form a single IP address and by default this is set to 4, which if you consider that the Thunderbird client alone requires at least 5 connections to be able to successfully negotiate an IMAP mail session, perhaps this will help to show where the problem lies, that is already 1 connection too many. Now imagine if all your family have mailboxes on the same server,and you are all using mobile phones to collect your email…voila, now “Unable to connect….” is easily explained!

In order to correct this problem we will need to modify the following 2 IMAP configuration parameters MAXDAEMONS and MAXPERIP and you can play with these settings dependent on your particular requirements, for a few family members the settings of:



should be sufficient…

However if you are a corporate entity with 50 users all working behind the same firewalled IP address then you should be thinking more along the lines of


and if you have a large numbe of users accessing mail services from their homes or outside of the office then you may also find that a MAXDAEMONS setting of in the region of 300-400 is required.

Do bear in mind that there is a reason for these limitations and that reason is that the more IMAP servers (MAXDAEMONS) and connections (MAXPERIP) that you allow will have an overhead in terms of memory and cpu resources that they require, so do not just set ridiculously high numbers, because this will impact on other services that your Web Server requires.

Just play with the settings gradually and you will find a setting that suits your requirements.

In order to make the modifications you will need ssh root access to your PLESK server, and you will need to log in using a suitable terminal emulator such as “putty”

Once you have logged in you will need to modify the /etc/courier-imap/imapd file using a suitable editor such as vi to modify the default MAXDAEMONS=40 and MAXPERIP=4 settings.

I have several family and small business users on my server and I seem to be able to run quite happily with setting of MAXDAEMONS=80 and MAXPERIP=40, so give those a try, but obviously you are free to try any setting that you feel will be suitable for your own situation.

Once you have made the changes then it would be a good idea to restart the mail services, which only takes a couple of seconds and is easily done with the following command:

# service courier-imap restart

Good luck and enjoy using IMAP