Last updated on 30 April 2026
Limits as of 30 April 2026
These limits are undergoing evaluation and are subject to change.
Also the limit types are subject to change, such as changing solely to a ‘Per Hosting Service’ limit.
For all Hosting Services: 1G, 10G, 100G, NVME and HDD for SE Asia and Oceania
| Email Processing Property | Per Minute Bucket | Per Hour Bucket |
|---|---|---|
| Per SMTP User | 100 burst, 10 refill/min | 1000 burst, 50 refill per hour |
| Per Sender Domain | 120 burst, 10 refill/min | Currently no per hour bucket |
A sent email will trigger all three buckets above: two ‘Per SMTP User’ buckets and one ‘Per Sender Domain’ bucket. So, although there is currently no ‘Per Sender Domain’ hourly bucket, a per user hourly bucket applies.
For each email processing property there is up two rate limits buckets, a per minute bucket and a per hour bucket.
The ‘Per SMTP User’ property is the SMTP logged in user name to send email. It is not necessarily the same as the envelope sender and if different the SMTP user name is not sent with email, but is logged.
The ‘Per Sender Domain’ property is the domain part of the envelope sender. This means if you send using addresses a@mydomain.com and b@mydomain.com then both share the same bucket pair for sender domain mydomain.com. However if you send from a@myotherdomain.com and b@myotherdomain.com then they both share a different bucket pair for myotherdomain.com.
There are additional buckets to prevent flooding of single email addresses.
A single outgoing email drops the level of each bucket by one. For an outgoing email not to be soft rejected, no bucket can be empty
A per minute bucket increases its level each minute by a fixed amount up to the maximum of its burst.
A per hour bucket increases its level each hour by a fixed amount up to the maximum of its burst.
The lowest burst is the maximum number of single outgoing emails that can be sent in a row without soft reject, provided the lowest burst bucket has been given time to fill up to its burst level again and the current level of higher burst level buckets is above or equal to the lower burst.
Considering ‘Per SMTP User’ buckets on their own.
With per minute bucket of 100 burst and 20 refill per minute with per hour bucket of 1000 burst and 100 refill per hour:
The maximum number of email that can be sent by a user in one clock minute slot without a soft reject is 100 (the lower burst).
The maximum number of email that can be sent by a user in 24 hours can be determined using the lower refill rate of 50 refill per hour, which is 1200 in 24 hours.
There are steps in place to prevent the local shell being adapted for use as an open email relay.