@andreasdueren said in Sharing custom SpamAssassin Rules:
Not sure if this is checking for the header content or arriving address
Good point. One way to find out
I've been transitioning away from aliases to wildcard, mostly for services that I wouldn't be sending mail from. My understanding is that anything to x@yourdomain.com will be fetched by the catch-all, so spammers send emails to see if you have a catch-all inbox or not. With the wildcard method, spammers need to target it specifically for it to work. For instance, you can set up something like:
*services@domain.com
netflixservices@domain.com
googleservices@domain.com
onetimepurchaseservices@domain.com
aldiservices@domain.com
etc..
Use multiple wildcards:
*crapps@
*yourinitials@
*family@
*groups@
and all of these would be "active" without you having to create it beforehand. It comes in handy when you need an email on the fly and want it to be identified with a specific service.
Edit: I've had my FedEx email address get compromised, but it was using a wildcard. In my FedEx account I updated my address by adding a number to the wildcard (fedex5services@domain.com). Then, I created a filter in roundcube for the old fedex address to send all incoming mail to the junk folder. I haven't seen a single address pass-through.
BTW, you can make wildcards less obvious (I believe in security thru obscurity) by abbreviating things, using initials, different languages, wordplay, etc.
https://docs.cloudron.io/email/#mail-aliases