VERIFIED SOLUTION i

Replace the standard email address reply to a relevant description in EngageOne Deliver

This can be achieved by setting the following in the From DIJ entry:

DDSDocValue name="From" type="text" len="13">mailbox&lt;mailbox@nn.be&gt;</DDSDocValue>

where
'mailbox&lt;mailbox@nn.be&gt;' will display the mailbox name, and it will still use the email address and,
the length 'len' value is the number of characters in the mailbox name, for e.g. Number of characters in the mailbox name 'mailbox@nn.be' is 13 characters. 

Below are possible scenarios of what this will give (mailbox)user@abc.com and how will the email address appear.

1.If From address is provided in the input data in the DIJ file/rest, it will used as From address (overrides the From address in the Outbound Profile).

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2.If the From address is not provided in the input data in the DIJ file/rest, the From address in the Outbound Profile will be used.
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3.If the From address is not provided in the input data in the DIJ file/rest and the From address in Outbound Profile is blank, no From address will be passed in the email. 
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UPDATED:  December 7, 2018