Do you confirm some of your clients use the POP3 protocol? Could you make a test?
- Disable POP3 protocol from “Email” page
- Increase custom quota to 5GB
- See what happens
Do you confirm some of your clients use the POP3 protocol? Could you make a test?
Yes
Some of my clients use the POP3 or IMAP
all clients use Thunderbird 52.5.2 (IMAP or POP3)
Some of my clients use Webmail Roundecube
Yes
same error