Time for which email covered the distance from sender to recipient. 

When the letter is created, the sender says creation date. When a letter comes to us, we look at the clock and know how much time the letter was on the way. 

The reason that this number may be inaccurate:

  • The sender pointed incorrect date
  • The sender misconfigured clock
  • The clock is not synchronized with world time

Causes when the letter is in the way for a long time:

  • Sender SMTP Server is busy
  • Email queued scheduling of tasks
  • Network or server error
  • Sender sent the email with a delay
  • Email with advertising or spam usually is sent postponed