Dates on Email

Life Technology
1

Can anyone explain how the dates on email work?

I use Outlook Express. What I am trying to determine is: When an email is sent out, how is the date stamped thereon?

I have an account with Hinet, which is on ms2.hinet.net. Obviously, here in Taiwan we are GMT + 08:00

I see four scenarios for date stamping on email which is launched into the internet from a person’s computer –
SENDING-BASED
#S1 the date/time of the email is indicated based on the date/time of the “outgoing” processing server ISP.
#S2 the date/time of the email is indicated based on the date/time of the sending computer, i.e. when the email was sent from the personal computer, based on the personal computer’s date/time.

RECEIVING-BASED
#S3 the date/time of the email is indicated based on the date/time of the “receiving” processing server ISP.
#S4 the date/time of the email is indicated based on the date/time of the receiving personal computer, i.e. when the email was received, based on the personal computer’s date/time.

[Notes: I would assume that any ISP would have a very accurate time-clock. However, the time-clock on any one person’s personal computer could be fast or slow.]

However, I note the following peculiarities:
(a) The clock on my computer here in Neihu, Taipei, is about ten minutes fast. If I send an email to myself, it indeed arrives in my Inbox with this date and time. This indicates that the SENDING BASED scenario #S2 is the correct one.

(b) I have email in my Outlook Express Inbox which is dated 2021/02/24 11:04 am. Such a date-stamp only seems possible with scenario #S2, i.e. the sending computer has been adjusted to this future date, and the email sent out carries this date. So, SENDING BASED scenario #S2 appears to be the correct one.

© I correspond by email with people in Washington, D.C., which is 12 hours behind Taiwan. (The people there definitely have their computers set to Washington, D.C. time.) They often email me between 3 and 4 in the afternoon. In my Outlook Express Inbox, I have many of these email with times indicated such as 3:14 am, or 3:46 am. This would appear to indicate that the email is being “date-stamped” as per the RECEIVING BASED scenarios #S3 or #S4, i.e. that the date-stamp is being done based the setting at the Taiwan ISP ms2.hinet.net or based on my personal computer’s setting. Clearly, email leaving Washington, D.C. at 3:30 pm August 15th and being registered in my Outlook Express Inbox at 3:30 am August 16th is not being date-stamped with Washington, D. C. time.

The above results are contradictory. Can anyone explain?

2

Richard,

You gave three examples, a), b), and c).

As you suspected, the most likely reason why the date was wrong on b) is because the sender has his clock set incorrectly on his computer.

As to your other questions, all e-mails have the sender’s time on them, but also contain information about what time zone they originated in.

For example, your buddies in D.C would have a time stamp saying 3:30PM (GMT - 4:00). This would give the receiver’s computer the information it needs to convert the sender’s time zone into the local time zone of the receiver.

In summary, scenario S2 is probably the correct one. That’s my basic understanding of it. Hope that helps.