Recovery Gmail password with an unknown mail service


New Email
Hi, I'm trying to recover the password of an another Gmail account I have (I created it about 2 years ago for backuping up some mails and files) and Google is offering me to send a security code to an E-mail address which its domain is like this : sig••••••••••••••.com

Does that ring any bell? I don't remember creating yet another account for recovery this one.
But in case anyone else knows how to look for a domain that stars with "sig' and has 17 letters I would appreciate it.