Access to e-mails from two or more computers

Issue:
Need to have access to all my e-mails from several location (home PC, work PC, etc)

Solution:
Set up one/several location(s) to Leave e-mail copy on server and the one (main computer) that should downloads without leaving copies

Source:
Leave Copy of Email on Email Server
www.basiccomputerinformation.ca/leave-copy-of-email-on-email-server

Problem:
It only works for INCOMING e-mails

Note to self:
"Leave Copy of Email on Email Server" setting on Outlook seems to related with INCOMING, not outgoing messages; has same meaning with "Remove copy from server after retrieving a message" setting on Mac Mail OSX
Source: How do I make sure I leave my messages on the Rogers Yahoo! server?