That is, only administrators will ever see the mailto: link. You'll find similar code in memberlist.php.
Exactly, I setup a test board to illustrate that for him tonight but he hasn't accessed it yet. There is some inconsistency in what admin permissions are needed to see the email icon, for instance the 'can manage users' permission gives you the link in viewprofile but not viewtopic oddly enough. I discovered this whole convoluted use case mix while troubleshooting a support topic over a year ago, this one to be exact. http://www.phpbb.com/community/viewtopic.php?p=9821105#p9821105
As as result of that topic I went through and documented every possible use case for sending email and the resulting workflow needed to achieve the desired result. While the OP's issue is not a bug since it is behaving exactly as it is coded to behave, the behavior is inconsistent between the two methods of sending email and I believe there is an opportunity to improve it so users can achieve the same result in who can send emails regardless of whether they are using the board to send emails or allowing direct emails. I really think you should reopen this ticket change it to type=Improvement and work out the discrepancies in behavior. Currently the permission 'can send emails' only controls the ability to email (regular)user to user if $config['board_email_form'] is 1, it has no effect if $config['board_email_form'] is 0 in which case it (it being emailing user -> user) is then controlled instead by 'hide e-mail addresses', which IMO it should not be.
Email icon should not display anywhere if you do not have permission to send emails
Permission setting should control ability to send emails regardless of email config values
If you have admin permission to view "hidden" email addresses that permission should display them in every view
*All the above comments assume that 'Users can contact me by e-mail: is Yes' since that variable also determines visibility of the email icon/link under both configurations.