necessity about virus software (trend micro so on)for iphone

I would like to know whether my cellphone is infected by malware etc.

because I use microsoft outlook app on cellphone.but I receive some fishing mails from someone and enterprise by the app. I research myself about measures to protect my device,I bought antivirus app and install on it some years ago.but spam mails like fishing mails doesn't stop now.parhaps I heared that Microsoft email account is more danger than other account (gmail etc)because it is free mail account so to speak.but gmail is free mail( no charge mean,I think)too,so the above reason is strange .

I don't know what to believe.

anyone help me,please.