Email delay to gmail recipients

Hello Mohammed Ahmed,

Thank you so much , i really appreciate you.

Product used:  

we are service providers ,so a colleaque tried to send out mail to the recipient aadamu@nercng.org but it shows delivered from his end but the recipient did not get the mail. so, i even tried to check SPF record for that domain nercng.org but found no record. so, below is the error message i found in fortimail