[iTunes] What happens during Email Accounts syncing between iPhone and iMac?

[Michael Prete]

I'm not clear exactly what happens (or is supposed to happen) when I  
select "Sync Selected Email Accounts" under the "Info" tab. I  
understand that when I sync contacts or calendars, that new info from  
either iPhone or iMac relating to Addresses or Calendar Events is  
exchanged so that both units have the same info. But what changes in  
the Email Accounts? It seems that if I download, read and delete  
email on my iPhone, it doesn't affect what happens on my iMac. I  
think I download, read and must delete the exact same items again on  
the iMac. So what syncs?

I'm still unable to avoid this repetitious handling the same mail  
items on iPhone and iMac, regardless of mail settings. I currently  
have the settings in Mail on iPhone (for POP accounts) set so that  
under Advanced settings,  Deleted Messages are "Removed After One  
Day" and under Incoming Settings, Delete from Server is set to "When  
removed from Inbox." For my two IMAP accounts under the Advanced  
settings/ Mailbox Behaviors, Deleted Mailbox is set to "Deleted  
Messages" and Advanced settings/Deleted Messages is set to "After one  
day".

Can someone offer insights or point to a good explanation?

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Michael Prete

More will be revealed.