The IMAP command “APPEND” (to INBOX.Drafts) failed with server error: Mailbox is full / Blocks limit exceeded / Inode limit exceeded (0.001 + 0.000 secs)

Thank you so much for your interest. this is a fascinating tech problem.

I wish I understood more about it.

We recently migrated our CPANEL hosting from a company called Vodien to Digital Pacific.

Since the migration:

Only Apple Mac users, using either Mac Mail or Outlook on a Macbook or IMac have a problem with the IMAP connection.

All platforms send and receive emails though Apple Macs do not save any drafts, sent, junk or any emails to the server. If they do, it is sporadic.

IPhone's, IPad and PC's running Outlook have absolutely no issue with the IMAP functionality. I have tested all platforms, on both existing email accounts and on brand new email accounts. All correctly move emails into draft , sent and junk folders on the server as would be the normal function.

Only on Macbook and IMac's running Mac Mail or Outlook do you receive error messages when,

1. writing a message: The IMAP command “APPEND” (to INBOX.Drafts) failed with server error: Mailbox is full / Blocks limit exceeded / Inode limit exceeded (0.001 + 0.000 secs) 
2. Sending a message: The IMAP command “APPEND” (to INBOX.Sent) failed with server error: Mailbox is full / Blocks limit exceeded / Inode limit exceeded (0.001 + 0.000 secs)
3. Or even moving a message to an established folder on the server: The IMAP command “APPEND” (to INBOX.ENQUIRIES) failed with server error: Mailbox is full / Blocks limit exceeded / Inode limit exceeded (0.001 + 0.000 secs)..

Thank you for any support or ideas you might have. I have tried clearing out all caches and restarting etc etc. could it be a PHP function that is not working?

Thanks Ben_Z1, yes I believe that there is an issue on the server but their support said it was not their problem since everything worked ok on PC's and Mac IOS and everything worked in Webmail.

It tried it on different Mac machines and tried changing the port settings to secure and insecure settings.

Emails can be sent and received but not moved automatically or manually into the sent, drafts, junk or any other folders on the server. When you run the connection doctor, not errors are found.

I was hoping someone out there might know what it is on a server that would create this issue only for Mac OS users. Then I could go back to the host and advise what needs to be checked or corrected.

Cheers and thanks for any advice.