Andrew McGlashan wrote:
On 15/02/2012 7:20 PM, Matthew Cengia wrote:
On 2012-02-15 19:03, Jason White wrote: [...]
based on a few minutes of reading, I couldn't find anything in RFC2821 that would require it.
FYI, this is obsoleted by RFC5321 now (and updated by 5336).
Okay, well it doesn't appear to be part of the standards, but it is painful for greylisting. Although I can understand that one IP may become blocked or have issues, whilst an alternate (sending) IP might be fine.
When you run into such a site, it is a good idea to (attempt to) notify the site's sysadmin that he is, indirectly, making life easier for spammers. After all, there's a slight chance that 1) they don't know there's a problem; 2) they're technically comptetent enough to fix it; and 3) enough sysadmins complain that they're actually motivated to do so. Ah, who am I kidding...