If you're using fastmail you don't even have to worry about that limit. If your email is example@fastmail.com and you are registering with http://www.onlinestore.com/
Just use onlinestore@example.fastmail.com and fastmail will make sure it arrives in your example@fastmail.com inbox.
Just use onlinestore@example.fastmail.com and fastmail will make sure it arrives in your example@fastmail.com inbox.
It's completely hassle free.