We're setting up a redirection-based mail server with a lot of complex moving parts, including the standard ones that apply to everyone like SPF/TLS as well as the more complex ones needed to ensure redirect mail gets accepted like SMTP authentication for Gmail, SRS, DKIM and the SPF complications that arise.
I've been sending messages to gmail and inspecting the headers myself, but it's tedious and easy to miss problems. What I'd like is a service where I can send an email from our server (or from a SMTP-authenticated Gmail account) and get a report about the various technologies and whether they are working or not.
Note that I'm not looking for a tool to assess a mail server from outside, as http://mxtoolbox.com/ already does a great job of that as well as many other things. Another similar tool with slightly different coverage is http://www.intodns.com/ Both of these are really useful but only for testing your server from the outside. I want a service that recieves email and assess the aspects that can only be tested at that point in the process.
http://dkimvalidator.com/
It seems to work really well so far in my testing. The homepage gives you an arbitrary, random address, you send an email to it, then submit the address to view results for the most recent email it got for that email.
The address can be anything, so you could also use a unique ID you come up with and work into your testing structures.
The output shows you the raw output then uses Perl tools to assess DKIM validity, SPF validity (inherently including SRS I guess) and a useful readout of Spam Assassin results. The Spam Assassin results in particular are really useful because they cover a lot of smaller issues (in my case, no UTF-8 declaration) that could affect your email even though they aren't directly related to the DKIM/SPF stuff that the tool was built for.
I think what your looking for is this tool, provided by Unlock the Inbox.