Currently default Logback SMTP appender sends one email per one log. But we need to squash consecutive logs into one email if they have the same message and/or stacktrace.

For example, there can be a property to define time in seconds to wait for the next same consecutive log event, and if time threshold is reached (or if log event with different message / stacktrace appeared in sequence), email should be created and delivered.

I did not yet started my own appender implementation which supports that feature, but I can do this and help with contribution if admins agree and somebody else in community needs this feature.