About two years ago I started a little experiment with my personal inbox that has been working surprisingly well.
I have a personal inbox, through which I handle all my freelance work, writing gigs, family and friends, banking communications, etc., and a separate company inbox, which is provided by my employer.
For a few weeks, I decided to try to only reply to email from new contacts in my personal inbox once a week: Sunday evenings, when things are quiet, and people don’t reply back as quickly as mid-week. These emails include prospective design and writing gigs, recruitment agencies, admin stuff like bills, requests for help or interviews, and other non-urgent requests. They do not include current clients, (genuinely) urgent requests and my family.
I use Gmail for my private account. When I get an email, I star it and archive it. As much as I can, I try not to read the details, or I know I’ll be thinking about it all the time, which will distract me until it’s actually time to focus on a response. On Sunday evenings, I’ll sit down and reply to all emails at once. Some weeks this takes longer than others, but most weeks, because I’m completely focused on this task, it can take between 15 to 45 minutes (unless there’s a particularly lengthy email that needs a lot of planning and thinking).
This has been working really well, and since I decided to give this a try I’ve never looked back. Not only does it save me time because I don’t get distracted from my work throughout the week, but it also makes sure that everyone that sent me a genuine contact request gets a reply within a reasonable timescale.