SMTP AutoSupport from ONTAP fails with "552 5.3.4 Error: message file too big"

Applies to

• ONTAP 9
• Autosupport
• SMTP

Issue

• ONTAP fails to send Autosupport by SMTP.
• EMS-LOG-FILE.GZ includes the following error:

[node1: notifyd: asup.smtp.drop:error]: AutoSupport mail (HA Group Notification from node1 (XXXXXXXX) XXXXX) was not sent. The system will drop the message.

• notifyd.gz includes the following error:

...
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:44) (message: DATA)
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:44) (message: 354 End data with .)
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:46) (message: 552 5.3.4 Error: message file too big)
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:46) (message: Connection #0 to host aa.bb.cc.dd left intact)
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:46) (message: Failed to transmit smtp asup 4597, curl error: Weird server reply)
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:46) (message: asup_job sent '/mroot/etc/log/autosupport/202411270000.0' mailserver=aa.bb.cc.dd fd=39 t=2557100 status=0)
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:46) (message: Failed to deliver smtp with subject: HA Group Notification from node1 (XXXXXXXX) NOTICE)
Wed Nov 27 2024 01:54:47 +09:00 [kern_notifyd:info:1754] (category: 1754:4597:deliver) (emittime: 11/27/2024 01:54:46) (message: update_counters: MIB: Setting mib status to SMTP FAILURE)