Mistake In an Email to Professor that is already sent out
The way I see it, you have two choices:

Do nothing - I do not endorse this, as it transmits the message that you do not care, or even worse, you did it on purpose;

Send another e-mail with the proper apologies (do not over-do it), and correct the mistake.


The message can be as simple as:

Dear ....
In previous e-mail I wrote: &quot;...ABC...&quot; while I intended to write &quot;...XYZ...&quot;. Please accept my apologies, this was totally unintended. I cannot even explain it to myself.
Yours...

Words may vary.