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Microsoft 365 - Tips and Tricks

Blocked Email Attachments

There are some attachments that will not send if you try to attach them to an email message. 

These attachments are: 

ade, adp, ani, bas, bat, chm, cmd, com, cpl, crt, dll, exe, hlp, hta, inf, ins, isp, js, jse, lnk, mdb, mde, msc, msi, msp, mst, pcd, pif, reg, scr, sct, shb, shs, vb, vbe, vbs, wri, wsc, wsf, wsh

*Note: An attached .zip file that contains one of the file types listed above, will also fail to send. 

Exchange Online

When to Use Caching with Your Mail Client

In general, you will experience better performance with your email program if you have caching enabled (generally enabled by default). Caching mail makes copies of your mail messages to your local hard drive, which is useful for accessing messages offline, with slow connections, or if often on the move. Without caching no mail will be available without a connection.

If you have a large mailbox (10 GB and over), it may be beneficial to disable caching or cache only for during a certain time period. Please refer to the following recommendations for using caching with your mail client:

  • Outlook 2011 or 2016 for Mac: Enable Caching
    • Caching is enabled by default on Mac OS X and you should not change this setting unless experiencing significant issues with Outlook performance.
    • Learn how to clear the cache in Outlook 2016 (same process should work for Outlook 2011). 
  • Outlook 2013 for Windows: Enable caching for 12 months.
    • If you have a relatively small mailbox (10 GB and under depending on hardware), you should not experience latency or performance issues with Outlook. In most cases, mailboxes will not be larger 10 GB over a 12 month period.
    • Learn how to adjust your Outlook 2013 cached mail settings.
  • Outlook 2010 for Windows: Enable caching.
    • If you begin to experience application pauses, especially when retrieving new messages, you may consider turning off caching. It is recommended to upgrade to Outlook 2013 in order to have more control over your caching settings.
    • Learn how to turn on/off cached exchange mode in Outlook 2010.
  • Apple Mail for Mac: Enable caching. 
    • Caching is enabled by default on Mac OS X and can cleared manually. You should not use this option unless experiencing significant issues with your Mail performance.
  • Outlook 2013 for Windows: Reduce OST File Size
    • Outlook 2013 allows a user to reduce the size of their offline Outlook Data File (.ost) which can also improve performance. To do this, go to File, open Account Settings then Email Account Properties. Click on the Advanced tab, then click Outlook Data File Settings, and then click Compact Now.

Clearing Nickname Cache in Outlook

To clear nickname cache in Outlook, follow the following steps: 

  1. Start to type a name in the address field of a new email. A nickname list will appear and can be browsed by scrolling up or down. 
  2. To delete a name from the list, simply highlight the name in question and hit the Delete key.