SMTP Error (452): Failed to set sender (4.3.1 Insufficient system storage).

[bristolxyz]

When attempting to send email from the web interface, getting this error:

SMTP Error (452): Failed to set sender "[email protected]" (4.3.1 Insufficient system storage).

I have increased the HD space to double what it was , now 160 GB, but no joy
Status check still shows low disk space:

"The disk has 0.09 GB space remaining."

Running On ESXI VM
Config'd as follows:

Ubuntu Linux (64-bit)
Compatibility
ESXi 6.7 and later (VM version 14)
VMware Tools
No
CPUs
4
Memory
12 GB
HD 160 GB

[JohnDoh]

That error comes from your SMTP server, it is not a Roundcube issue.