I had a discussion here in the support forums, on the available options for activating a newly registered user.

One of the outcomes was, that one of the links in the email notification for the activation request which the Admin receives, leads to the activation:

Use this link to activate the account:

What does not become clear from this wording is that the activation happens INSTANTLY on clicking that link. This however might be a bad thing to happen, because the Admin fails to verify the rest of the registration data (the email only shows the user name), yet the (perhaps fraudulent) user and receive also instant email notification about his account having been activated.

What I'm trying to say here is that (unexperienced) Admin might - due to unclear wording - accidentally activate/approve new users, although not having the intention to do so.

My suggestion would be to make the wording unambiguous by actually adding the word INSTANTLY:

Use this link to INSTANTLY activate the account:

(I even would stick to the all upper case spelling).

Addendum

The discussion under the above forum link continued and Robert (who’s into phpBB since nearly 14 years) wrote:

actually, that message is exact. if you click it you activate the user.
if it was going to take you to a page so you can look at the registration info it would say something like, I don't know,
Use this link to view the user's profile:   

My response to that is as follows:

In german we say „Wer lesen kann, ist klar im Vorteil“ (Them who reads, clearly has an advantage). Unfortunately, in these busy times, one often doesn't read everything in detail, but only cross-reads ... at best.

Hello,

The account owned by "Dumb Bob" has been deactivated or newly created, you
should check the details of this user (if required) and handle it
appropriately.

Use this link to view the user's profile:
http://clowns.springfield.com/memberlist.php?mode=viewprofile&u=59

Use this link to activate the account:
http://clowns.springfield.com/ucp.php?mode=activate&u=59&k=6X19C8HE

-- 
Best regards
Sideshow Bob
Administrator Springfield Clownery Academy

The problem is a) that the actual notification message is a bit longer than just those two lines and that b) your argument requires the Admin/Mod to CAREFULLY read the message and compare the description of both links. The problem herein is that view does not imply that it leads to profile view which also allows activation, especially due to the fact the the following link clearly does say/imply activate (but then again fails to say that it happens instantly on clicking the link).

Changing the wording to Use this link to INSTANTLY activate the account: or even less ambiguous: Click this link to INSTANTLY activate the account: would leave much less questions.

The problem with these discussions is always the perspective/background knowledge: You – having joined phpBB 14 years ago – know exactly what’s behind these links. I, who have been using it since barely 3 weeks, learned it now. Anyone who’s new to phpBB administration might/will also have to learn it through trial and error first. But: There are so many things to learn, so many trials and errors to make, when it comes to phpBB administration, every single detail which makes things less ambiguous is worth the effort IMO.