Quota issue with mail user even though quotas are off!

I am running into an issue where a mail user is hitting disk space limitations even though quotas are turned off.

Virtualmin > System Settings > Virtualmin Configuration > Set quotas for domain and mail users? No is checked.

A new mail user connected to their mail account via IMAP is trying to upload about 80MB of mail messages from a folder on their local computer and they are getting this error:

The IMAP command “APPEND” (to Old Inbox) failed with server error: Not enough disk space.

I have lots of space on the server.

[root@vps Maildir]# df -h /
Filesystem Size Used Avail Use% Mounted on
/dev/simfs 40G 3.3G 36G 9% /

Any ideas why this is happening?

I think that setting only effects users created after it was changed. What is the allowed quota for the new mail user who is getting the error?

If you really want unlimited quota, a better idea would be to use a account plan with everything set to unlimited.

Thanks for the input!

When quotas are turned off the “Quota and home directory settings” section in the admin of an email user’s account does not show quota info.

All domains on the server are managed by me. The only external input is mail from a few users on a couple of the domains so I am not concerned about the unlimited settings.

What you mentioned above made me look at something I have never used before in Virtualmin and that is account plans. I looked in there and saw that the default plan was listing limits on “Quota for entire server”. I have removed those by setting to unlimited, clicked Save and Apply and am still running into the issue.

So with quotas off and account plan set to unlimited and verification that the mail account (and the domain) were created after the quotas were disabled what are my next options to find out what is causing the issue?