The ping of incoming mail is, admittedly, very tempting. But every mail as soon as it arrives makes it difficult to concentrate on your other work. Limit the handling of your incoming mails to three fixed moments per day. And why not mute that tempting ping.
Not every mail is equally important. U can easily use flags and colours to prioritise. That will tell you which mails to handle first later on. You can also filter incoming mails with a mailfilter. In its Start tab, Outlook, lets you set different filters (unread, with attachment, categorised, marked, by date, sent to, etc.). Of course it’s also best to use your professional email address for business communication only. Your private address can then be reserved for family and friends.
Try to strive towards an empty inbox at the end of each day. There should really only be two types of emails in your Inbox: unread messages and mails that require further follow-up. All other messages belong in other mail folders (i.e.: Old Messages). All you need to do is to move read messages to their appropriate archive folders. And if you need to find such an older message, you can use the built-in search functionality in your mail programme.
Is your Inbox really overflowing, then you can also consider automatic archiving. You can use the search function to find all messages that precede a certain date. Or you can add parameters to your own taste and needs (read, marked, flagged, …). Simply select all those messages and put them in a separate folder.
What with spam and so called ‘gray mail’ such as newsletters? Use the unsubscribe links that those mails should legally have. U can also mark a message as spam so that the next one will automatically be relegated to your junkmail.