How E-mail Servers Manages Time Across Continents ? GMT Differs for each place

[longtimeago 0]

So i am sure that the first thing that every one notes when you get an email is the subject of the email along with some other important information. That is the Time and the date when this mail was sent. Now days Gmail even offers another information in each mail which states how many hours before the mail was sent . . But how ever the information about the date and time in the header of the mail which we see is accurate and useful. Now it just makes me think what is that the mail servers use inorder to keep track of the exact date and time . Just take this scenario i create a Gmail from India and i move to USA and when i am in USA, my IP will record a US IP address. Now when some one sends me a mail from India to my Gmail and when i open it in USA hopefully i will see the time in US Timings and not in Indian timings. Now let me be more precise, if some one sends a mail to me from India in the evening 6 that is 6 PM and at the same time if i open my mail from USA, what time is to be displayed ?? i am sure that it will display the US timings. But if i use the Indian Proxy and open the mail will it show 6 PM ?Hope some one atleast get what i mean ? Im kind of sure that mail servers must be going for GMT and display the time and date. Ya that is fine. But how about the above scenario ?