Backup failures to complete successfully

My wife has hundreds of thousands of email messages in this application. We were able to run the back-up successfully when we first set her up in the application but ever since then the back-up has failed, citing inadequate storage capacity. That is not the case. The back-up location has plenty of capacity. Is there something that I can do to successfully run a back-up or is eM Client just not a good application for someone with so many emails? Every time I try to run the back-up it figuratively brings our computer to its knees, significantly slowing down the speed at which the other programs we are running perform.

Is the backup being saved to an external device?
What version of eMC are you using?
Can you display the exact error you are getting?

How much mail do you have, how far back does it go and how big are your mailboxes?

I’ve had some issues with my mailbox size as well. For the most part things are OK, but every so often it bogs down for me too. I haven’t tried the backup. I might try it tonight when I don’t need to do anything just in case it slows things down like you were mentioning.


The backup is being saved to a thumb drive.
We are using version 8.2.1473 (04b618f).
Unfortunately, no. I was doing a backup this afternoon. It was running for about 7 hours and just aborted without leaving an error message.

There are about 211,000 unread messages in the Inbox and local folders.
I have no idea how many read messages there are but I don’t think there are very many because I think my wife has been deleting messages that she’s read.
Included in the total above, there are over 130,000 messages in one local folder I set up when I migrated all of my wife’s email messages from the Inbox of our former email client to eM Client.

Could it be that the thumb drive format will only allow individual files to be no larger than 4gb? It could be that the thumb drive was formatted as FAT32 rather than NTFS. Here’s some information to read prior to doing anything to the drive, File too large for USB drive? Here is how to fix it.

Have you tried saving the backup to your HD?


This might be a brilliant explanation.

I just started another backup to the desktop. I really would want the backup to be to an external drive of some sort but let’s see if the backup to the desktop works and then go from there.

This is going to take many hours but I will give you an update tomorrow on how it went.

Thanks very much for your help.


I have a folder called backups and backup to that folder with many applications. Then every night the backup folder is backed up to an external USB HDD (2 tb for about $65.) This gives me 3 copies, the original and 2 backups. As @sunriseal said, if you total file size is > 4 GB then it must be formatted as NTFS, not fat32. - I recommend then doing a cloud backup to have a copy off-site in case of theft or fire etc.

Thumb drives are not reliable media and will eventually bite you.

Thank you very much for your advice. I have a comfort level working with PCs but I would never consider myself a technician. I have heard of the terms NTFS and fat32 but that’s about the extent of my knowledge about them.

Having said all this, it’s taken about two days to successfully run a back-up to our laptop’s hard drive but that process ended today. The file was over 7 GB so I was definitely bumping up against limitations when using a thumb drive.

I do have an external hard drive. I periodically backup my system to this hard drive so my WD Smartware product should backup an eM Client backup on my desktop.

Thanks again for your help.

Thank you very much for your help. I successfully completed a backup to our laptop hard drive today. The file was just over 7 GB so that was never going to work with our thumb drive. I just didn’t know that.

It is VERY understandable that you did not know that, now you do and can pass it on in the future. We have all been in that position before and we all learn something new every day, just keep an open mind.

domingo 24 octubre 2021 :: 1453hrs (UTC +01:00)

Hi @Gary_Yunker

Should you decide that you want to be able to write a large file to a thumb/flash/USB… read on.

SOLUTION - Format in NTFS to overcome 4Gb limit

Formatting the device as NTFS will make it unwriteable on a Mac computer. Most Mac computers can read NTFS, but not write.
NTFS is a journaled file system, this creates more read/write activities. Therefore, it MAY decrease life expectancy of your device.
Once the device is formatted as NTFS, you MUST use “Safely Remove Hardware” to remove your device.

STEP 1 - Optimize the thumb/flash/USB drive for performance

  1. Plug in the device to the PC.
  2. Open Device Manager
  3. On the right side expand Disk Drives
  4. Right-click on the thumb/flash/USB drive, then select Properties.
  5. Click the Policy tab.
  6. Select Optimize for performance, then click OK.

STEP 2 - Format the thumb/flash/USB drive

  1. Insert flash/USB drive
  2. In Explorer Right-click on the thumb/flash/USB drive, then select Format.
  3. In the File system list, click NTFS.
  4. Click Start.
  5. Click OK to start formatting.
  6. That’s it

¡Saludos desde la soleada Sevilla en España!
¡Mis mejores deseos y mantente a salvo!


Hablo español, luego portugués e inglés, con conocimiento de varios otros idiomas.

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