Connect to Outlook is one of the important feature in SharePoint which enables you to collaborate with Microsoft Outlook. Microsoft SharePoint 2013 allows you to synchronize your Document Library or List to the Outlook Mailbox. your synchronized list or library appears in outlook under “SharePoint Lists”
You can synchronize a SharePoint contact list between Outlook 2013 and SharePoint 2013. This enables you to store, share, and manage SharePoint contacts more efficiently in Outlook. You can also take the contact list offline, work with the contacts, bring them back online, and then synchronize them either from Outlook 2010 or SharePoint 2010.
When you go to any library or list , you find it surprised to see “Connect to Outlook” Option is greyed out. The reason is due to JS files which is not loaded.
MDS (Minimal Download Strategy) is a feature which loads on necessary controls on each page load. This would increase your page performance in all SharePoint pages. If MDS is enabled in your site, Connect to Outlook option is disabled. Period. Now if you want to enable this option, this just one more F5 or Refresh the Page, your Connect to Outlook option is enabled now.
Another options is to disable MDS feature at the site collection level which is not advisable if you are considering the performance.
Happy SharePointing Folks 🙂