While sending the mail through the Uipath an error is popping up

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Send SMTP Mail Message: 535: 5.7.8 Username and Password not accepted. Learn more at
5.7.8 Check Gmail through other email platforms - Gmail Help z10-20020aa79e4a000000b0053b9e5d365bsm6962833pfq.216 - gsmtp

This the error i have getting .i know i have to keep Less Secure App Access on but there is no on or Off button available .How to resolve this problem