[logback-user] error log : one email per request

Hi all, I am using SMTPAppender for error report in a web application. Using default setting, the logger sends one email per log message. However, I was trying make it like this : * All the messages logged during one request handling are grouped into one email, and the email is sent only when error occurs (i.e. at least one of log events is at level ERROR) Is there any easy way to implement this? Thank you. Best, Weipeng