I provide my email address with the +companyname suffix on the local part as a way to filter my email into various folders based on the To header contents.
Unfortunately, many websites are configured to reject email addresses that contain a plus character. I've also encountered websites in the past that did accept the + character when creating the account where the email address serves as the user name, but then could not log in because their log in form rejected the + character in the user name.
Unfortunately, many websites are configured to reject email addresses that contain a plus character. I've also encountered websites in the past that did accept the + character when creating the account where the email address serves as the user name, but then could not log in because their log in form rejected the + character in the user name.