For some users on some sites, the "Share via email"-button does not appear

Hi.

On our SPO intranet, some of our users, on some of our sites, are missing the "Share via e-mail"-button. It appears to be due to a permission setting of some sorts, as one of our power users do get the button when signing in with his admin account, but not with his regular account. 

I'm not quite sure which setting to look for, so if anyone could point me in the right direction I'd appreciate it. 

Best regards,

Ken