Hello,
Myself and @Jbhunley have been noticing some issues with Special:EmailUser. Unlike previously, it takes an unusual amount of time to send a copy of an email to yourself and sometimes hours or more for the email to arrive at its target (or in one case, time travel backwards...). Recently, there was an issue with Wikimedia being DDOS'd....could this be a lingering aftereffect?
Emails seem to be coming through again. Just sent one using the interface and immediately had my copy of it in my inbox. Haven't received any via the interface to check otherwise though (for the other half of the problem).
I will go ahead and close this if I notice it working fully/properly.
I don't use email much so I can not really provide feedback. Before closing this, you may wish to reach out to other users. Preferably via village pump.