Added the following properties to 'login.properties' file:

com.openexchange.ajax.login.maxRateTimeWindow specifies the rate limit time window in which to track incoming login requests. The rate limit acts like a sliding window time frame; meaning that it considers only requests that fit into time windows from current time stamp:
window-end :=
window-start := -end -
Default value is 300000 (5 minutes)

com.openexchange.ajax.login.maxRate specifies the rate limit that applies to incoming login requests. A client that exceeds that limit will receive a 429