How to restore a "mail_data.dat" file in a new DataBase

Hi all,

I have back-up files of an old EM data base : (with a big 25 Gb in “mail_data.dat”). I’d like to open these e-mails in a new EM client.

I’ve tried to reinstall a new EM client & copy the back-up files in the \User\AppData\Roaming\eM Client\ folder but it doesn’t work.

Is there really a way to restore these files & if so, what would be the specific process?

Thank you very much,



Any EM expert to help me?



Hi Joshua,

You can restore the backed-up database in eM Client > Menu > File > Restore.


Hi Russel, I am contacting you directly because I see you are an employee of eM Client. I posted something two weeks ago about an error I keep getting and have had no response from any support member. I have copied and pasted it below. As I indicate my mail is working but this error pops up every time I open it and every few minutes after. Can you help me with this please?
Thank you, Daniel.

I am running windows 10 and using an old mail account. Same as Hotmail and now This problem only happens in eM client. Every time I open my mail I get the same error message. I hit ignore all and hide and it goes away for a while. All along my send and receive is working just fine. I have noticed that when I send myself an email it is sent to the junk folder instead of my inbox. I have added my email to contacts a couple times now to see if that would help but no luck there. Attached is the error and the logs. I have opened the account setting and reentered them but it keeps popping up. Can some one help me please.  

Hi Russel,

Thanks for your help.
Actually I don’t have a regular backed-up database. As I didn’t know it was possible to do it I simply copy these files in the previous data base :

Is it possible to restore them, especially “mail_data.dat”?

I’ve tried - File > Restore > The folder containing “mail_data.dat”, but it’s not recognised as a file to restore.



Hi Daniel - could you please open a dedicated topic for your request? This one is related to my own issue. Thank you.

I did that two weeks ago. Sorry but I thought I was contacting Russel who works for eM Client

No, actually you’re posting in a topic I’ve opened a few days ago - please, update your own thread because I’d like to stay focused on the issue I’ve raised by creating this specific topic. So could you please delete these messages & post them on your own original topic ? Thanks in advance.

I understand that now. Sorry but they wont let me delete anything. If you know a way let me know. You only have the option to delete something for a very short time, like minutes. I was told this before by one of the support people. Very sorry for causing any problem for you.

Yes, once someone has commented on your post, you cannot delete it.

Daniel, if you require support directly from eM Client, please open a support ticket. You will need a Pro License to do that.