On 4/12/06, Matthew Black <black@csulb.edu> wrote:
I haven't seen any succinct justification for providing a 550 message rejection for positively-identified spam versus silently dropping the message. Lots of how-to instructions but no whys.
For viruses - fine. But you are not going to find any spam filter in the world that doesnt have false positives. And in such cases its always a good idea to let the sender know his email didnt get through. Like for example - you see a large webmail provider whose hosts and domains keep getting forged into spam, misread the headers and block that provider. In such cases, its your users who arent getting a lot of valid email from their friends and relatives who are using that provider, and 550'ing instead of trashing email saves the senders, and their provider, quite lot of time that'd otherwise be spent troubleshooting the issue. Plus, 5xx smtp rejects tend to save your bandwidth a bit compared to accepting the entire email (not that it matters on a small university domain where your userbase is going to be fairly small, and bandwidth available quite generous .. but for larger sites, or sites with bandwidth issues, that's definitely a concern) --srs -- Suresh Ramasubramanian (ops.lists@gmail.com)