Sometimes little things slip through the cracks when sending an email like a typo or sending the email twice. We kick ourselves for these little mistakes and call ourselves an idiot but in reality you got your message across and people forgive and forget quicker than you think, sometimes they may not even notice.
So, before you go correcting the mistake and resending the email or send another email apologizing for the duplicate, just realize that your readers may or may not have noticed the mistake and have already moved on. An extra email would just seem annoying, after the fact.
If you are constantly flooding inboxes with typos or other mistakes, then you have a problem. Otherwise just chalk it up as a mistake and move on. We tend to over think and worry for our customers too much sometimes. They’ve probably made mistakes in life too.
So just be careful and proofread your emails before sending and check all your links. If mistakes happen every once in a while it’s no big deal, don’t beat yourself up over it.