File with .eml extension "bounce" synchronization between clients (Windows) almost forever

Hello,
we are facing a strange behaviour of the synchronization on Windows PCs when it comes to file with .eml extension (that is used by e-mail clients like Thunderbird when they export messages in the file system) .
We saw this happening many times between colleagues sharing libraries, when mail messages were archived in SeaDrive. For long time we supposed it was caused by a bad interaction with antivirus, but we verified it is not the case. It happens, from what it is evident from web modification history, that in specific situation an .eml file saved by on a PC, seems to be modified (without human intervention) by another PC, so the file is synchronized back to the other PC, but after a while the log says the file is modified (always without intervention) so synchronized back to the original PC, and this loop can continue undefinetively unless something is operated. We found in the log (always the web library modification history) this synchronization ping-pong creates about one log line per minute (or more), so easily filling up the log with thousand lines, eating CPU cycles and causing synchronization troubles in general.

The file with .eml extension does not require to be created by a e-mail client.

A text file saved with .eml extension is enough.

Our environment:
Server Version: 7.1.15
Clients: OS: Windows 10 SeaDrive 2.0.18 (PC1 named “DP”, PC2 named “nb-palmi”)
In the following procedure the same user (Me, that is Dario Palmisano) is synchronizing the same library on two different PCs, but in our environment different colleagues sharing a library were involved in this pathologic synchronization loop.

Below I will describe the simplest way (we found several variation) to reproduce the problem.

Step 1: on “DP” (PC1) Desktop create a text file containing “Test file” (whatever will work) then name it as “Test_file.eml”
Step 2: Copy the “Test_file.eml” in the SeaDrive Library, as consenquence of the copy the file will result as cached
Step 3: Once the “Test_file.eml” is synchronized also in the “nb-palmi” (PC2), select it, right-click and click on “Always keep on this device”. This step will fire the continuous, fast resinchronization of the file on both computers (one at a time), without my intervention, showing in the web log (Modification History) the following list:

My Library Modification History
Tip: a snapshot will be generated after modification, which records the library state after the modification.

Description Time Modifier Device / Version
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano DP / seadrive_2.0.18
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano nb-palmi / seadrive_2.0.18
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano DP / seadrive_2.0.18
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano nb-palmi / seadrive_2.0.18
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano DP / seadrive_2.0.18
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano nb-palmi / seadrive_2.0.18
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano DP / seadrive_2.0.18
Modified “Test_file.eml”.Details 2021-12-03 Dario Palmisano nb-palmi / seadrive_2.0.18
Added “Test_file.eml”.Details 2021-12-03 Dario Palmisano DP / seadrive_2.0.18

This will continue until in one of the two PCs you will select the file “Test_file.eml”, right-click and click on “Free up space”.

Just to conclude I will say that, I saw in the forum other posts about .eml files but no specific reference to what I referred. I will add that it is possible that more than two PCs can be involved in this “problem” wasting even more resources and slowing synchronization.
We reproduced the behavior on PCs with no antivirus installed to avoid any bad interaction, so what was here reported is supposed by us as caused by SeaDrive only.

We appreciated SeaDrive a lot so we provided this contribution to improve it and as such we hope the developers will appreciate it.
Should my description result not clear enough, please get in touch.
Thanks for your kind attention
Dario

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This reminds me of a similar case, maybe this fix can help you: Seafile Client 6.1.0 EML files and antivirus - #11 by Jonathan

Thanks for your answer, but the environment is different we are using SeaDrive 2.0.18, so I do not see the similarity (apart from involving .eml files).
Please detail your arguments.
Thanks again

I agree, I thought the server was also involved in the problem, but it seems to be a client-only issue. Maybe SeaDrive has the same problem as the Seafile client. Sorry this was not very helpful.

@Dario I believe it’s the same problem as described at Seafile Client 6.1.0 EML files and antivirus - #12 by daniel.pan . This is because .eml files’ timestamp can be changed without changing the contents, by some program in the OS. Such “changes” are ignored in Seafile client to avoid this issue. SeaDrive doesn’t include such fix. We’ll fix it in the next release.

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Thanks for your message.
Is this new SeaDrive release date already known?
Thanks for all your work and efforts!

It’ll be released by the end of this year.

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