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Services such as email, calendars, contacts, task management and a suite of collaboration tools using SharePoint are provided to the University by the Nexus Service. Click here to read more about Nexus.

The University currently in the process of migrating to Nexus365, providide by Microsoft. For help configuring Outlook during and after you have been migrated to this service please refer to this page:

General Advice on using Outlook

  1. Setting up Outlook for the first time? Use the Outlook Nexus Setup Program. Read more
  2. Using RSS and Internet Calendar subscriptions is known to cause synchronisation issues, with symptoms such as Outlook running very slowly, not showing up-to-date calendar information, or reporting connection failures. Read more
  3. Wherever possible it is strongly recommended not to use PST (archive) files. These can cause synchronising issues and cause Outlook to ‘pause’ when processing them in the background. Read more
  4. If you have more than 500 folders this may cause problems, including if they are split across different mailboxes that you have open. Read more
  5. Try to keep your mailbox size to a minimum, save attachments elsewhere and remove old items. Read more
  6. Only have the additional mailboxes that you need open and close others when you aren’t using them. Read more
  7. Don’t have Outlook set to start-up automatically on logon, this may cause additional delays in it opening whilst it the workstation is still working on background tasks prior to logon. Read more
  8. Use Nexus Webmail for quick access to mailboxes when using a different workstation, this provides quick and easy access to mailboxes without having to configure Outlook or cache mailboxes. Read more

For further information on the configuration of your mailbox and Outlook please click here. For guidance on using other clients please click here. The Nexus Service Team have provided a number of hints and tips around using the service which are on the Nexus Support pages. If you need any further assistance log a support call (requires SSO credentials)


Configuring Outlook

Before you use Outlook you will need to configure Outlook for use with Nexus, the University's e-mail system. If you have been migrated to Nexus365 please refer to the updated support page:

You can do this by opening the “Nexus Outlook Setup Program” from the Start Menu

  1. Open Nexus Outlook Setup Program by clicking the Start button . In the search box, type Outlook, and then, in the list of results, click Outlook Nexus Setup Program.
  2. When prompted ensure that your username is in the form of then type in your Single Sign-on password.

Running this program will configure Outlook for use with Nexus. You will only need to run this configuration the first time you use a CONNECT workstation. After this your settings will be remembered and you can open Outlook directly.


RSS Feeds and Internet Calendars

Using RSS and Internet Calendar subscriptions is known to cause synchronisation issues, with symptoms such as Outlook running very slowly, not showing up-to-date calendar information, or reporting connection failures.

To check if you have any RSS Feeds

  1. Within Outlook click on the File menu and the on the Account Settings button
  2. Select Account Settings from the drop down list.
  3. In the Account Settings window click the RSS Feeds tab.
  4. Any active RSS feeds you have will be listed. To remove any highlight the feed name and click on Remove.

To disable RSS Feeds

  1. Within Outlook click on File menu and then Options.
  2. In the Outlook Options window click on Advanced.
  3. Scroll down to the RSS Feeds section and untick Synchronise RSS Feeds to the Common Feed List (CFL) in Windows.

To check if you have Internet Calendar Subscriptions

  1. Within Outlook click on the File menu and the on the Account Settings button
  2. Select Account Settings from the drop down list.
  3. In the Account Settings window click the Internet Calendars tab.
  4. Any active Internet Calendars you have will be listed. To remove any highlight the calendar name and click on Remove.


Outlook Data (PST) Files

We recommend that all email is stored within Nexus and that staff do not export mail to archive files. Outlook data and archive files (known as PST files) can very easily become corrupt. This files are not stored within the Nexus system and by default are stored on the local hard disk of the machine you configure them on. These files will not be backed up.

The use of PST files is also known to cause performance issues during certain operations in Outlook. This can cause the application to 'freeze' whilst it synchronizes the PST file, with issues especially noticeable when you switch into and out of folders that contain a large number of items.

If you use Outlook to connect to other email accounts, such as POP3 or IMAP, Outlook will also store these email accounts to a local Outlook data file. We do not recommend that you use Outlook to connect to any other mail sources outside of Nexus.

For further information on expanding your mailbox size please refer to the Nexus support pages.


Large numbers of folders

Having more than 500 folders may cause problems. The 500 folders are counted across all mailboxes you have open that are stored on the same mailbox server, not just your own mailbox. This is a default Exchange limit when accessing mail via Outlook and will cause caching problems and synchronisation errors for users that are above this limit. For further information on this please refer to the Nexus support pages. If you are over this limit of folders you may receive an insufficient memory error when attempting to access folders, as per the Microsoft guidance here. (This article specifically references Public Folders however the same applies to primary and additional mailboxes.)


Mailbox size

As your mailbox size increases, more resources are needed to open each folder. If you have a large number of items in any single folder, you are likely to experience performance issues. A significant amount of your mailbox quota is likely to be taken up by attachments. These can be stored elsewhere rather than in your mailbox.

If you have more than 50,000 items in a single folder, views other than Arrange By: Date can be slower. It is recommend by Microsoft that you move several items in these larger folders to separate folders in the same store or to an archive store and that you use Arrange By: Date when you run Outlook 2010. Please be mindful of the 500 folders limit when making any changes


Additional Mailboxes

The more mailboxes you have open the longer Outlook will take to synchronise. If you have mailboxes open which you don’t frequently use consider only opening them when you need them, rather than having them permanently open. For further guidance on delegation and sharing within Nexus please see the Nexus support pages.

To close a mailbox

You can close unused mailboxes by right clicking the mailbox and clicking Close [mailbox name] from the menu. If you do not see the option to close please email asking them to turn off auto-mapping on that mailbox. Once auto-mapping has been turned off the mailbox will automatically disappear.

To add a mailbox

  1. Within Outlook click on the File menu and the on the Account Settings button
  2. Select Account Settings from the drop down list.
  3. Select the Email tab, click your account in the list, then click Change and then click More Settings.
  4. On the Advanced tab, under Open these additional mailboxes, click Add and enter the mailbox name tht you wish to add to your profile.


Outlook Start-up

Although you are able to start opening applications immediately after logging on when you see your desktop, there are still processes finishing in the background that aren’t visible to you. Waiting a few minutes after your desktop appears will allow those processes to complete and your computer will then be able to use all of its resources to open your application.

If you have chosen to run Outlook immediately after your computer starts (by placing these in the start up folder) you should be aware that Outlook will be slower to start-up as there are other tasks completing in the background just after login.


Nexus Webmail

Nexus webmail allows you to quickly access your email from any machine, both in Oxford and anywhere else that you have an internet connection. It provides easy access to your mailbox and any other mailbox that you have full delegated access to. This does not require Outlook to be configured or mailboxes to be cached on the local machine. Fore more information on webmail please refer to the Nexus Web Email Guides.


Further Information on mailbox and Outlook configurations

Outlook is configured to run in Cached Exchange Mode – this means that a copy of your mailbox is store on the local drive of your computer. When you use Outlook on a workstation for the first time it will download this copy of your mailbox in the background. Depending on the size of your mailbox this can take some time and Outlook will run slower during this process. If you open a folder and it appears empty, check the bottom right hand corner of the Outlook window and you will see that Outlook is downloading the items from the email server.

Once your mailbox has finished caching a full copy will be store on your workstation drive (there is also a live copy on the email server). Every time you close and restart outlook it will contact the email server and check for new mail. This process compares the mailbox on the email server with the copy on your C drive and downloads any changes – depending on the size of your mailbox, the number of items in your mailbox and the amount of time since you last had Outlook open, this process can take some time. In addition to your primary mailbox any additional mailboxes you have open in Outlook are also cached to your machine.

The cached mailboxes are stored in what is known as an OST files (Offline Data File). The size of your OST files depends on the size of the mailboxes and if you have a large OST file this can experiences performance problems within Outlook. The absolute maximum recommended size is 50GB but however Microsoft have issued the below guidance: highlight issues experiences as the size of your OST increases:

  • Up to 5 gigabytes (GB): This file size should provide a good user experience on most hardware.
  • Between 5 and 10 GB: This file size is typically hardware dependent. Therefore, if you have a fast hard disk and lots of RAM, your experience will be better. However, slower hard disk drives, such as drives that are typically found on portable computers or early-generation solid-state drives (SSDs), experience some application pauses when the drives respond. 
  • More than 10 GB: When the .ost file reaches this size, short pauses begin to occur on most hardware.
  • Very large (25 GB or larger): An .ost file of this size increases the frequency of short pauses, especially while you are downloading new email messages.


Other email clients (including Thunderbird)

If you do use another email client such as Thunderbird client please ensure that any cached mailboxes are stored outside of your user profile, i.e. store them within Local Settings. Instructions for changing this setting within Thunderbird can be found here:

Please note that the Service Desk use Outlook to access Nexus and will only be able to provide limited support for other email applications.

Written by IT Services. Latest revision 2 April 2020