You’re right to be hesitant to hand over your social security number to someone you don’t know. Con artists are creative in the ways they appeal to ego and desire in order to make an easy score. Still, some publications do require social security numbers for writers on their payroll, even if it’s just a one-time shot. While reprints aren’t common in magazines and journals, they do happen. And anthologies often republish essays, articles or stories that have already been published. So, this could go either way.
The fact that the request for personal information came in the first correspondence would be a red flag to me, but that still doesn’t mean it’s a shady request. Research the publication or press with which the editor claims affiliation. Is it respected? How long has it been around? (You’ll want to do this to determine if you want them to republish your article anyway.) Don’t simply go by the quality of the website. Many people engaged in fraud know how to make a site look slick and professional. Find the site through an Internet search or by typing the URL in to the browser yourself. If you simply click a link in the email sent to you, you may end up thinking you’re safe in Kansas when, in fact, you’re dazzled but quite vulnerable in Oz. Make sure there’s a genuine connection between the person sending you the email and the publication or press. You should be able to find this editor’s name and contact information on the website. If not, a quick call can confirm this.
If everything seems on the up and up, it may be a genuine request. Still, I’d at least have a phone conversation—one that you initiate by calling the number of the press or publication—before coughing up all the requested materials. All that being said, listen to your instincts. If things still don’t feel right to you or if the deal seems too good to be true, skip it.