Which header do you set to prevent Outlook from forwarding an email (literally)?
66665
How to prevent an email from accidentally being forwarded?
135604
Can I change email content without stopping a journey?
1832
Prevent mail being marked as spam
29293
Gmail filters/labels: Force email to stay in Inbox?
152317
Block local (unix) users from sending mail
64613
How can I switch back to Hotmail from Outlook.com
67509
How to block "via" senders in Gmail
152808
How to Filter Emails Forwarded to Gmail Alias?
61905
Can you have two different names for the same alternative ("send mail as") email address in Gmail?
118446
Is it possible to create a Gmail filter that works on arbitrary headers?
15998
Email authentication without modifying DNS records
87226
Outlook 2013 / Windows 8.1: Delete e-mail from notification toast
32124
Can Outlook send multiple simultaneous emails to different people without doing a bcc?
145853
can't send email to addresses at my own domain
58695
How to set Outlook 2010 to use signatures outside of the default signature folder?
5327
Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User?
39819
How to make Outlook 2010 minimize when I try to close it?