When submitting a paper to a journal, often a cover letter to the editor is submitted as well. When this letter is sent by mail / uploaded to the journal's website, do I need to sign the cover letter? And if yes, how? With a certified electronic signature, or with a digital scan of my handwritten signature?
No, you don't need to sign it. (At least that's been my experience with every journal I've dealt with.) My cover letters just tend to be PDF files (uploaded to the journal site) that end like
< List of authors (printed names) >
There are actually very few times when a signature (either scanned or posted) is mandatory. In the journals I've edited (mainly in the health and medical fields) we would require some form of signature for contractual arrangements such as in the case of a supplement or a commissioned piece such as an editorial, when the type of submission requires it such as a case report and the author and patient submit consent letters to us, or when we
We don't require a formal signature for cover letters, but we do appreciate it. We need to know that the author stands by the statements in the cover letter as, for example, when the author asserts that the submission is not being considered anywhere. This can be accomplished in a number of ways and a signature is one of them. At the very least, a signed letter shows respect for classic codes of etiquette.
(Who here remembers having to submit manuscripts prepared on typewriters?)