Hi, The number of phishing or otherwise compromised accounts is needing an automation to manage it. Last night the spammers waited until the evening and simultaneously used 3 compromised accounts to send spam over secure smtp. A nagios alert on number of messages in the queue was our only alarm, and in only a couple of hours the reputation of the server and domain is damaged for awhile (both in and out).
I added smtpd_recipient_limit=20 to the options for secured SMTP. The error it produced when tested (with Thunderbird) is confusing: The size of the message you are trying to send exceeds a temporary size limit of the server. The message was not sent; try to reduce the message size or wait some time and try again. The server responded: 4.5.3 Error: too many recipients. If the user patiently reads to the end, the last statement is the only thing they need to know. However, the previous statements are wrong and misleading. How can this error be made better?
