Details
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New Feature
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Status: Closed
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Major
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Resolution: Fixed
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Description
Why
Rate limiting is one of the common features. Examples: SaaS is one https://www.fastmail.help/hc/en-us/articles/1500000277382-Account-limits#sending/receiving, https://support.google.com/mail/answer/22839
They limit how many emails you can send/receive from/to each email account over a given period of time.
We believe the rate-limiting will help James has more control of the resource and easy to dynamic config the user policy. It also complements the storage quota.
How
- Create a new sub maven module for this extension. This extension will be dropped by default in one James installation (not of a runtime dependency)
- The rate limit will have 2 criteria: number of emails and total size of emails
- Create 3 mailets:
- PerSenderRateLimit is per sender
- PerRecipientRateLimit is per recipient
- GlobalRateLimit for everyone
The mailetcontainer configuration will look like:
<mailet matcher="All" class="PerSenderRateLimit"> (<redisURL>...</redisURL> + creds?) <!-- Appended before the type (count/size) and the sender mail address to store the current rate in Redis --> <redisKeyPrefix>xxx</redisKeyPrefix> <period>1hour</period> <count>100<count> <size>1GB</size> </mailet> <mailet matcher="All" class="PerRecipientRateLimit"> (<redisURL>...</redisURL> + creds?) <!-- Appended before the type (count/size) and the sender mail address to store the current rate in Redis --> <redisKeyPrefix>xxx</redisKeyPrefix> <period>1hour</period> <count>100<count> <size>1GB</size> </mailet> <mailet matcher="All" class="GlobalRateLimit"> (<redisURL>...</redisURL> + creds?) <!-- Appended before the type (count/size) and the sender mail address to store the current rate in Redis --> <redisKeyPrefix>xxx</redisKeyPrefix> <period>1hour</period> <count>100<count> <recipients>100<recipients> <size>1GB</size> <sizeForAllRecipients>5GB</sizeForAllRecipients> <exceededProcessor>tooMuchMails</exceededProcessor> </mailet>
- Create an interface RateLimiter, which will evaluate the current rate limit and return whether the result is acceptable or exceeded.
- Create the implement InmemoryRateLimiter, which use guava-rate-limiter
- Create a configuration POJO RedisRateLimiterConfiguration(Duration period, URL redisServerURL).
- Create the implement RedisRateLimiter, which will use Redis to store the current rate of each email. Use https://lettuce.io/ for the non-blocking Redis driver.
- Write the document such as a setup, and provide a mailetcontainer sample file.
References
- https://www.baeldung.com/guava-rate-limiter
- https://github.com/lettuce-io/lettuce-core#reactive-api