E-mail sent has not been sent at correct time.

[Pdrowsky]

So, i had an test to deliver to my professor 19h max, and i have sent it 18h54, but outlook didn't send it till 19h32 for some unknown reason and now my professor refuses to believe that i have sent the e-mail on the correct time and that it's not my fault that the app delayed it by itself.

I used the mail app on windows 10 to send the e-mail and never had that problem before. Is there any way i can show him that the e-mail was sent at the correct time? (the e-mail message itself shows 19h32 as sent, but at that time i wasn't even on the computer anymore). He is not accepting the files modification time as proof of the sending, so i am looking for a proof of the delay on that sending so i can not be taken as guilty for the delay.

[#2]

 Hello.  The reasons for the delay can be many but proof of confirmation will not be shown! The main reason may be the lack of access to the Internet, due to an ongoing update, the attachment e.g. was quite large and the download the first time failed , -too low battery, etc. Your mistake was not to immediately check if the mail server accepted the task to be carried out! If you could prove the probable cause and what it was about!