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Email - de-duplication in Gmail, G Suite for Domains, and xMail
This article explains the concept of de-duplication within email systems. Under certain circumstances in Gmail, G Suite for Domains (formerly known as Google Apps), and Exchange, mail is de-duplicated resulting in recipients only receiving one copy of a message sent to the recipient multiple times, or recipients not receiving messages sent via uchicago.edu to their Google accounts.
Gmail and G Suite for Domains
If a user forwards their uchicago.edu mail to a gmail.com or G Suite for Domains example.com and then tries to send a message from Gmail/G Suite to their uchicago.edu address, they will never receive it in their Gmail/G Suite inbox. Google has message de-duplication as documented here:http://support.google.com/mail/bin/answer.py?hl=en&answer=6588
This also happens if a user sends to @lists.uchicago.edu address from Gmail/G Suite for Domains. If the user is a subscriber to the @lists.uchicago.edu address, she will never receive the message as distributed by the lists.uchicago.edu server.
Bob@gmail.com, is a subscriber to email@example.com. Bob sends a message to firstname.lastname@example.org. Bob will never see the distributed message from email@example.com in the Gmail inbox.
Bob, firstname.lastname@example.org, forwards their mail to their private Gmail account, email@example.com. Bob sends a message from Gmail to their uchicago.edu account, firstname.lastname@example.org, to test if mail forwarding works. Bob will never see the message in the Gmail inbox.
If an xMail user is a subscriber of two @lists.uchicago.edu address and a single message is sent to both lists, the xMail user will only receive one copy of the distributed message.
Bob, an xMail user, is a subscriber for email@example.com and firstname.lastname@example.org. Sally sends a message To: email@example.com and Cc: firstname.lastname@example.org. Bob will receive this message once, and it may appear to come from either email@example.com or firstname.lastname@example.org.