Please open a separate thread to discuss the import issues, with as many details as possible.

Please try to import through kmailcvt. File -> Import messages.

Now I actually ended up in the same situation and can't find anything which fixes it. Heh.

I opened a new topic regarding this problem...thanks...

einar wrote:Are you using any filters for POP?

I have a similar problem, i just deleted a pop filter and it goes better
https://bugs.kde.org/show_bug.cgi?id=310694

The pop filters make problems finaly ...

Dimitrios wrote:

einar wrote:Are you using any filters for POP?

I have a similar problem, i just deleted a pop filter and it goes better
https://bugs.kde.org/show_bug.cgi?id=310694

The pop filters make problems finaly ...

It did n't help a lot

In 4.12.0, it suddenly started to work again.

https://bugs.kde.org/show_bug.cgi?id=322958

The comment #4 fix my problem. In my case the problem was local-mail resource.

SOLVED
I noticed one reason causing this with KMail 4.14.1 in Debian jessie.
I have 2 e-mail accounts in different e-mail services (doesn't matter I think).

Symptom:
-Account 1 works after boot, but soon after when I click received mail in account 2 it hangs for ever as described in original question.
-Then also account 1 cannot show content after this problem appears.

Fix:
-I verified problematic account side by side using web-mail UI and noticed that this was caused after I had removed subfolder from account2 (using other machine/client)
-After I removed 'missing' folder also from KMail UI, everything worked as should.

So I think at least in my case it was endlessly trying to retrieve folder taht cannot be found from server.
Not saying this works for all, but worth trying.

$ uname -a
Linux ws09 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-1 (2016-03-06) x86_64 GNU/Linux
$ kmail --version
Qt: 4.8.6
KDE Development Platform: 4.14.2
KMail: 4.14.1