- bitdefender.com - Business product inquiry form - "Please provide a valid email"
- iptorrents.com - "That doesn't look like a valid email address."
- wwws.klm.com.cy - "Sorry, something went wrong..." when updating profile email address.
- lot.com - book.lot.com: "The information that you entered is not correct. Please verify and try again."
- lufthansa.com - Adding an email address: "Your entry is invalid. Please enter an e-mail address in the e-mail format (example@domain.com). (60030)"
- norwegian.com - Changing an email address: "Username is invalid".
- secure.square-enix.com - Changing an email address: "The e-mail address is invalid. Please enter a valid e-mail address."
- techtarget.com - The unsubscribe function does not work. Example for "user+tag@example.com": "There was an error processing your request. user tag@example.com: We could not find the necessary data in the URL."
- theentertainerme.com - Unsubsribe links in email messages do not work.
- travel.b-europe.com - "Please enter a valid email address".
- uralairlines.ru - Markenting emails are sent to "
<part after the plus sign>@<domain>
". - vk.com - Changing an email address: "Incorrect email."
exchange12rocks/naughty-plus-in-local-part
List of services which process email-addresses with a plus sign in local-part incorrectly