iphone 7 email flags turn red

Is this an Exchange account? It seems I read in another thread sometime in the past that for some reason, attempts to change the flag color in Exchange accounts will not work. It appears it may be something to do with the Exchange server, but I don't remember exactly.

To SravanKrA: Normally that is true, however I've seen this mentioned in the past.

Flags do not change colour. You need to select different colour flags.

Are you referring to colour different of flags between iPhone and Mac

Ada