Processing incorrectly formatted syslog messages

[1kUHuiswkvj7spRO]

Hello all,
I have an appliance that sends logs through the syslog protocol. For some reason, it does not follow any standards in regards to the message formatting. Now I understand that you can specify a regular expression to apply to the message, and declare attributes and records for fluentd to use. I'm doing this currently with another appliance that does not follow RFC standards, which is currently working. The problem I am having is fluentd rejecting the parsing of the data. I've tested my regex against an online validator located here: http://fluentular.herokuapp.com/ and everything checks out. I know the format declaration is deprecated. Could it be failing to parse the message data from lack of a timestamp? I'm not sure what else I'm missing.

Example of raw message, along with error message from fluentd:

[warn]: #6 failed to parse message data="<23> outbound/smtp: 127.0.0.1 1656088196-1413736624438b0001-xa4AuP 0 0 SEND ENC 1 2CD8D8DCEC11 250 2.6.0 <> [InternalId=] 25875 bytes in 0.059, 421.965 KB/sec Queued mail for delivery [x.x.x.x]:25"

Configuration:

<source>
  @type syslog
  port 20025
  bind x.x.x.x
  tag cuda
  format /\<(?<pri>\d+)\>\s+(?<ident>.+?)\:\s+(?<message>.*)/
  <transport udp>
  </transport>
  message_length_limit 16384
</source>
...
<match barracuda.**>
  @type file
  path /var/log/cuda/cuda
  <format>
    @type ltsv
  </format>
  append true
  <buffer>
    @type memory
    flush_mode immediate
    flush_thread_burst_interval 0
  </buffer>
</match>