Slogging through an overflowing inbox is one of the hardest parts about returning from vacation, or any time out of the office. Get through your email faster by reading it in "last in, first out" order. Often the issues cluttering your inbox are figured out by the time you return, so reading the most recent emails first helps you see which items still need your immediate attention.
Image from centralasian.
Of course, you'll often need to read a whole thread to get context or other key information, but by checking the last email first, you can see if it is something to address now or save to catch up on later. Better yet, follow up directly with the person who has the issue to see where they are now that you're back, and if they actually need anything from you at all. Filtering your inbox in this way allows you to focus your energy on getting important things done first so you hit the ground running after vacation.