Mail attachments (.eml) sent from IBM client /web cannot be opened by non Notes Client/Verse users. They can open .eml file with IBM notes if it is installed there. or else, they can open with outlook as well. They can open with notepad/notepad++ as well ( they will not be able to see any image , will be seen in plain text).
Expecting .eml viewer to be part of IBM Docs Viewer with VOP and Verse on Cloud