Since the recent mail problems our Network Development engineers have spent lots of time, in conjunction with Critical Path, examining our mail platform to reduce the possibility of mail queues or delays.
As a result of this work we have identified a number of changes we can make, which will improve the efficiency of the mail platform. These changes will also eliminate the occasional instances of mail being delayed on our mxcore servers.
The changes are detailed below:
We currently have a limit on the number of emails our relay servers can dequeue to our mxcore servers in any single connection, we are planning to remove this limit and therefore increase the number of emails we can process per connection. This will reduce the number of connections required to send emails, as well as speeding up the delivery time. This primarily concentrates on improving the delivery time of emails sent between PlusNet email addresses or hosted domains.
We currently reject mail from senders with no reverse DNS, we will be changing this so that less DNS queries are required, thus saving even more processing time. We anticipate that this will reduce possible delays on this part of the process from 2-4 seconds to zero seconds.
We will also be making config changes to our spam detection process. Currently we pass mail through numerous spam detection applications, and when a mail is categorically identified as spam it is passed to our mail collection servers for delivery. We are planning on changing this process so that when a mail is marked as definite spam it is delivered immediately, via which ever option the customer has chosen. This will reduce the possibility of mail queues, and therefore delays.
We will be performing these changes in stages, firstly rolling to one server and completing full testing, then to all our mxlast servers and completing full testing. If both these stages pass testing we will then begin rollout to the rest of our mxcore servers.
Due to this approach we don't expect all of these changes to have been fully rolled out until late next week, but we feel it necessary to take a slower approach and test all eventualities before we make changes across the entire mail platform.