I can't send SMS to some my contact who has iMessage

Hi guys,

I'm using the 14.7.1 version of iOS on my iPhone , from a few days age I can't send the sms to one of my contact who has iMessage on his E-mail and I add it to his contact on my phone .

before when I hole the message icon in contacts app , I could chose his number(SMS) or his e-mail (iMessage) to send text but now I can just send text to his iMessage (E-mail).

how can I fix it like before ?