We are currently seeing a significant "dynamite phishing" campaign of faked emails with the subject "firstname.lastname@example.org will be deleted from our server" which attempt to lure you into giving your login details to a third party. These emails have faked ("spoofed") senders making it look like they come from your own website.
We strongly recommend to delete those emails without opening them. Any user who has or may have followed the instructions in the email must change his login details immediately, including any identical login details at other websites.
Our antispam is now removing this specific email at 100% accuracy, however pishing emails often change rapidly in content so that some customers may still receive a copy.