If you rarely use e-mail, then after a while you can completely forget it.
Despite the fact that this does not happen often, there are proven ways to find out your e-mail address.
Try to use the content of the site,Giving you mail. Let's say you did not leave the account and you can access your username. Most often it is the main component of the email address. Add the "dog" sign and the domain to it. Suppose, if the login is vopros, and the site learn-myself.com, then the e-mail will be firstname.lastname@example.org. To find out if you were wrong in guessing, try sending some email to this mail.
Some sites provide a choice of severalDomains to the login. If you can not remember it, you can try all the options. As a rule, there are not more than four of them. Follow the same rules - send a letter to yourself and select the one that will reach the recipient.
If you left someone your electronicAddress, then contact him and ask to remind your e-mail. Also, you can ask your friends about whether they remember your email. Often close people know your address and can help. Also, you should contact your colleagues at work who can send you important information.
If you have access to the mail, but you do not rememberOwn address, just look in the "Sent" folder. As a rule, in the field "from whom" your e-mail will be indicated, also you can contact the technical support service of the site, which in 99% of cases will help to solve the situation.