I, like many people have a difficult time with email. It's something that is essential to everything I do, but it can get in the way. Over the years, there have been a number of methodologies and tactics used to handle email. Inbox zero, example, example.
If you look around for the best advice on email, you'll likely run into advice something along the lines of "check email less" or "only check email once-per-day" you get the idea.
Checking email in a limited manner, or once-per-day has never worked for me. I have different clients with different needs and expectations. I work on number projects with varying scales, cadences, and timelines. There's value in keeping at least a moderately consistent hand on my inbox. Still, it's not healthy (or nearly productive) for me to be working out of that all day. Constantly planning, re-planning, coordinating, etc. When do you get the work done?
Here's what has worked for me. I call it 9-1-5.
The idea is pretty simple. I'm going to let you down, but stick with me. The goal is to limit time in the inbox, stay responsive to clients, and not allow the inbox to become overrun and overwhelming to deal with. I hate digging through an un-checked pile of messages.
3 simple checks throughout the day. I've allowed up to 30min, but the goal is as little time as necessary. The better I am about being consistent with the schedule, the more efficient the check-ins becomes resulting in less time.
9am, 1pm, and 4:30 (complete by 5).
I don't check my email before 9am. As a morning person, this is a big deal. I stay focused on work and projects. There's no point in sending emails before 9, so why waste my precious focus time even looking at them before then. Most people aren't working before 9am and the perceived expectation is that I'm not either. At 9, I open my inbox and go through my sorting and responding process.
Again at 1pm (or following lunch) and finally at 4:30pm. The goal is to have that email off and out of my life by 5.
The second check is at 1pm. There's just a 4 hour gap where I potentially have not "been responsive" to somebody during the work day (and it's likely less than that depending on when they reached out). That's more than reasonable.
I've found that this cadence allows me to keep a nice and clean inbox, allows interaction with important clients and contacts who might have expectations that I should be available or responsive throughout the day, and gives substantial "air-coverage" to have time outside of email-mode to produce work.
Here's my process. Anything with a quick response gets an immediate reply. Anything that requires a longer response or requires work on my part gets scheduled in my task management software. I follow up with a note if necessary to give the client the feel-goods that I'm on it.
This could be information related to an existing project, a request for a new project etc.
I create a task and attach the email in the notes section to that task. I use the Mac mail app and in macOS, iOS, and iPadOS you can drag and drop an email into other applications and it creates a direct link to the email message. I'm then free to archive the message. When I get around to the task, I'm able to easily reference the message again (if it has necessary information) or respond to the person once the action is completed.
I've found that setting these boundaries with email has freed up a lot of work time and focus time throughout the day. I hope maybe this can help you as well.
As strange as it may seem to schedule the time with yourself, I've found it to be helpful. By prioritizing the time, it keeps me from feeling like I am not staying up on things during the non email-mode times. Additionally it help gain perspective on how much time is actually being spent on email, planning, follow up, coordinating, etc.