Could someone possibly tell me if anything I'm saying here is wrong... I'm totally baffled by this new ACL - it looks like it allows only one email per hour in to the server from any particular address. 1 per hour ?! are you kidding ? It looks like the default limit is 1.2 / 1h which, according to the explanation here http://www.exim-new-users.co.uk/content/view/65/39/ (section 39.30) means 1.2 messages per hour. How can you have .2 of a message ? So basically, under the new ACL - if a host sends more than 1 message per hour in to the server, that host is "ratelimited" i.e the email is rejected - "temporarily". is this like greylisting ? Does it delay the message and ask the sending mta to retry ? I dont think so. I think it returns the message to the sender saying something like - sorry youve reached your 1 email per hour quota - please try later. Example from my log.... temporarily rejected connection in "connect" ACL: "Host is ratelimited (2.0/1h max:1.2)" The sender has sent 2 emails into the server within an hour - so the connection is "temporarily rejected". Thats pretty crap if you ask me. Its perfectly normal for people to send 5 or 6 emails to each other within an hour - then theres corporate mail servers and of course ISP and other mail providers such as hotmail etc etc - where one mail server could realistically send 10 or 20 messages to different domains or addresses on your server within an hour. Apart from disabling this ACL completely, which seems to be the only sensible option - is there anything that could be done to improve this ? Can the 1.2 / 1h rate be changed to something a bit more realistic ?