I use a web service that sends reports to my clients via e-mail with my e-mail address as the return address but the “from” address is like this: email@example.com on behalf of firstname.lastname@example.org. Is this going to cause me problems anywhere? The web service is unable (or unwilling) to port through my mail-in-a-box.
as far as your service provider isn’t sending mail in your name directly, it’s all good. As far as I understand, your service provider just sets the header value Reply-To to your eMail address. This should work just fine and will not cause any problems with DKIM / SPF.
All the best, Tim