URLs should be based on pageID instead of pageTitle
By default, a confluence URL contains the space and page title.
eg: http://confluence.mydomain.org:8090/display/KEY/Page+Title+Goes+Here
When the page is renamed or moved to another location, the URL changes.
This behaviour is not ideal / wanted.

Examples:
When a task is created, or somebody is mentioned, an e-mail notification is sent.
When a page title or location changes afterward, the e-mail link is broken.
The same goes of course for bookmarks.
This is frustrating for people as in a lot of cases, pages are being renamed / moved frequently.

Confluence supports URLs based on the fixed page ID, which would overcome the above issue.
eg; http://confluence.mydomain.org:8090/pages/viewpage.action?pageId=12345
(if a page title contains non-ascii character, the URL is automatically based on pageID).
However, I cannot find a way to setup pageID urls by default.

For manual copy/paste sharing, we promote the "Link to this page" feature.
Unfortunately, most mail references to confluence are generated by the system.
What strikes me is that at the bottom of a generated mail, you have the links "view page", "comment" and "like".
"View page" and "comment" use to the standard link. However "like" uses the pageID link.