If you are running Vesta and email is suddenly not being delivered. You can check the mail log located at /var/log/exim4/mainlog

You may find an error that looks like this:

2021-12-19 03:39:42 1mxheU-000374-0o == mail@domain.com R=localuser T=local_delivery defer (-1): Malformed value “0MM” (expansion of “${extract{6}{:}{${lookup{$l$….

This is a bug in Vesta caused by incorrect Exim config written if you have set the mailbox quota to unlimited.

To fix it, modify the mailbox within the Vesta panel and set the quota to a large value for example 20000 MB.

• Login to Vesta ->
• User -> Login to the user account ->
• Mail ->
• Hover over the domain and click on the ->
• List x Accounts ->
• Click Edit next to the mailbox in question ->
• Enter 20000 in the Quota field (click on the unlimited symbol if it won't let you enter a value ->
• Click Save