Or, better yet, use subaddressing, also known as plus addressing.
Then when you call customer service to report the problem, you wind up talking to someone with no internet messaging knowledge at all, who tells you that a '+' is invalid in email addresses because their website doesn't accept it and they've never seen it used there.
My bank was one of those when they changed to using Intuit's services. It was pretty funny, getting them to admit that the email address I had been using with them for years was suddenly not valid according to their website, and they were even discussing this "invalid email address" with me BY EMAIL. They accepted education, however, after I sat in the office of the director for online services for half an hour explaining the problem, and their website is now better. It does have the wonderful property of wanting to verify my identity by calling or emailing me every time I log in from a "new" location, and their method of keeping track of old locations routinely forgets I've been logged in from there before.
Neobits.com, however, remains willfully ignorant. When customer service said "the plus sign is not valid", I explained that it was, indeed, and when no further progress in solving the problem was apparent, I said "you've just lost this order" and hung up.
When I really need to create a temporary address and the destination won't accept a '+', I create an address in my own domain (usually along the lines of "f**k[insert company name here]@...").
Perhaps the funniest one is that many years ago I registered for linked-in using "email@example.com", and they actually registered the account and were still listing that address when I went back a couple of months ago. They were telling me when I logged in that one of my addresses was bouncing, and it wasn't until I went deep into the account that I saw they were still trying to send to an example.com address.