Do not start an email with this sentence or any variation on it: “Sorry for the delay in replying”
You are busy.
Your inbox gets full.
Sometimes it takes a while to get back to people.
Sometimes you miss something and notice it 2 weeks later.
This happens to everyone. Even the person you are now replying to.
The content of the reply is what’s important.
E-mail is asynchronous communication.
The beauty of e-mail is that you can write when it is convenient for you. And the other person can respond when it is convenient for them.
Urgent issues should not be dealt with by e-mail. Ever.
Most things are not urgent.
Each of us contributes to the culture of urgency by our actions.
If you apologize for how long it took, you are saying that e-mail should be speedy. If you don’t you are contributing to slowing things down.
What is speedy about e-mail is the time it takes to travel from one person to another.
The medium has no necessary effect on how long it takes the recipient to process the information, craft a reply, and send it off. Nor does it have any necessary effect on the priority of the message for the recipient.
You get to decide your own priorities.
You get to plan your own activities.
You do not need to explain yourself.
If you need a system for dealing with e-mail that keeps you in control, I highly recommend Email Triage from Productive Flourishing.