Mailbox compression & quotas

[GrandAdmiral]

Hi

We're currently in the process of converting all our client's mailboxes from maildir to mdbox. As part of this process I've enabled mailbox compression which has shaved about 20% off our server storage usage, very happy with that result!

However, I'm a little confused about how this is reflected to the customer in terms of quota usage. Taking an educated guess, I'd say the storage savings are reflected on their cPanel disk usage but the mailbox quota is still calculated using the uncompressed size.

Is that correct?

 

[cPanelMichael]

Hello,

The compressed mails should be reflected in the email account's disk space usage (which is part of the overall account's disk space usage). However, note that the system will only compress recently created and delivered messages after enabling "Compress Messages". It does not compress all existing emails that have already been delivered.

Thank you.

 

[GrandAdmiral]

It does not compress all existing emails that have already been delivered.

I knew about that limitation so we've been converting from maildir to mdbox to overcome this. There's been a 20% reduction in total disk usage so compression is active, but the individual email account quotas don't seem to have changed to reflect this.

For example I have one email account which on cPanel Webmail shows 6.97GB used, but when I tally up the backing files it shows 4.68GB usage.

 

[cPanelMichael]

Hello,

Could you open a support ticket using the link in my signature so we can take a closer look?

Thank you.

 

[GrandAdmiral]

Done, request ID 9013199

 

[Hedloff]

Did you find out the cause of this?
We're looking at converting old servers from maildir to mdbox also. If we do so, old emails will not be compressed, only converted to mdbox?
So we do not save any disk space?

 

[cPanelMichael]

Did you find out the cause of this?

Hello,

To update, here's the relevant part of the response from one of our Technical Analysts in the support ticket:

I can confirm that the email account will reflect the uncompressed size of the mail folder. The actual size of the mail directory is what will be reflected in the overall cPanel account's disk usage in terms of WHM quotas. This keeps the mailbox size consistent in the customer's viewpoint but allows for the optimization in your actual disk space.

Thank you.

 

[Hedloff]

So it will be a gap between what is actually used?
Not quite sure I understand the logic in that.
So doing compression will save customer disk space, but it is not consistent and will show different on each email account? That will only cause customers asking about it....

 

[cPanelMichael]

Hi @Hedloff,

Internal case CPANEL-17326 was implemented in cPanel & WHM version 70 to help reduce the confusion when customers check their disk usage in cPanel:

Fixed case CPANEL-17326: Clarify meaning of “Email Accounts” in cPanel Disk Usage.

The "Disk Usage" in cPanel will display the following note:

†Email account storage may occupy less space on the disk if you use compression or hard-link optimizations designed to save space. Email account storage does not include the metadata that the system uses to store email.

‡The files outside of your home directory, the metadata that the system uses to store email in the mail directory, or the files that you do not have permission to access.

Thank you.

 

[actihost]

Hello, Does enabling mailbox compression will affect server performance? We would like to use this feature to save storage but just want to make sure about that because we host hundreds of cpanel accounts with thousand of mailboxes. Thanks!

 

[cPRex]

@actihost - the compression feature only works on recent messages, so it won't compress all the files in mailboxes. That will ensure that there is minimal performance impact from this tool.

You can find more details on this here:

https://support.cpanel.net/hc/en-us/articles/4403256232599-How-to-enable-email-compression