Catch-all
As a catch-all (including catch-all forwarding ) is an address forwarding any string in the first part of an email - or WWW designated address to a mailbox or a website.
Catch-all for emails
In the case of e-mails, a mail forwarding or an associated mailbox is called catch-all, in which all e-mails that are addressed to any local part ( local-part ) within a domain converge.
An example: Only the email address [email protected] is set up for the domain example.com . In addition, a catch-all forwarding to [email protected] is set for example.com . If an email is now received on the server at [email protected] , this email goes directly to the mailbox of [email protected] , although this email address was not previously set up for the server / MTA .
The catch-all forwarding causes all e-mails to destination addresses of the form 'any valid character string' @ domain to converge in the same mailbox. This can serve as backscatter protection, as an e-mail to an unknown recipient is not (back) sent to the sender e-mail address, which is often falsified in the case of spam , phishing or the spread of malware , so that the owner is harassed of fake addresses is excluded by backscatter. However, it makes more sense to configure the accepting mail host in such a way that it does not even accept the mails that arrive at non-existent addresses or that are recognized as spam, phishing or infected, so that no backscatter can arise from rejections that occur later.
Accepting emails to any address is also a disadvantage. The delivery attempts of spam / phishing / malware with invented recipient addresses or backscatter of mails with invented sender addresses from the own domain (which in turn are used as recipient addresses for the bounces ) cannot be carried out early after the (mostly non-existent) recipient address will be rejected. Significantly more resources are used for the acceptance and any further checks for spam, phishing or malware that may be required, as well as for storing the unwanted mail. Catch-All is therefore hardly suitable for the efficient operation of a mail server. The e-mails additionally received in this way should also be viewed by a person, since otherwise, for example, typing errors in the address lead to unnoticed incorrect / non-delivery. This leads to a further significant consumption of resources.
Catch-all for websites (also "domain wildcards")
If a catch-all function is set up for an Internet domain, this means that any character string entered as a sublevel domain is forwarded to a specific host , such as the second level domain. What is special about the catch-all function is that although the sublevel domain does not physically exist, it is forwarded to a host that has been set up, regardless of which character string is entered as the subdomain.
An example: A catch-all function has been set up for the domain example.com . The user enters xyz.example.com in his browser. A redirect to example.com takes place , although the subdomain xyz does not exist.
However, you should be careful when using a catch-all function. Trademark rights can be violated by forwarding them. This can be assumed in the event that the second-level domain is purely descriptive (for example, Warenhaus.de ) and when a protected name is entered, it is redirected to the domain owner's website (for example, quelle.warenhaus.de ). Since the Internet user does not know that any character string will be forwarded, he will assume that the company Quelle offers products under the domain warhaus.de or is at least economically connected. This can already be sufficient to assume a trademark infringement . German courts have ruled accordingly with regard to name infringement. In Austria, the Supreme Court did not classify the catch-all function as a trademark infringement, but assumed that it was anti- competitive from the point of view of inadmissible channeling of customer flows . An overview of the assessment under trademark law can be found in Maassen / Psczolla in MarkenR 07/08 2006, pp. 304–309.