What would be a more formal way to say something like
The data has all been processed by now, so there's no need for further action
in an email?
I'm worried that "by now" might sound a little aggressive.
One easy way to do it is to simply strike the two words altogether:
The data has all been processed, so there's no need for further action
Another trick would be to do some rearranging and rewording:
Now that the data has all been processed, there's no need for further action
There is nothing informal about "by now" (nor are emails noted for a high degree of formality).
Your point about your example sounding somewhat aggressive has nothing to do with formality, but about perception and good manners. I can see that in certain contexts many would feel the example to be dismissive or denigrating, but I doubt that merely replacing "by now" would alter the perceived tone.
Thank you for your offer, but the data have already been processed.
I see no reason of using by now here. From what I know we use by now for reckoning
•They must have arrived by now.
•You should've been in bed by now.
I'd rather use already in this context
The data has been processed already, so there's no need for further action