Nice email client but it doesn't seem to work

I’m using the latest free version with 2 email accounts, my GMail account works fine but my broadband ISP’s IMAP and SMTP just doesn’t work. Before anyone says “it must be your ISP that’s at fault”, I’m also using Thunderbird and it works just fine with my ISP email with IMAP and SMTP. I’ve copied the mail server connection settings from Thunderbird into emClient, but no joy, emClient repeatedly reports errors connecting to my ISP’s IMAP and SMTP servers.

I can see the emails in my Inbox but any other folders show no messages, even though there are emails in those folders.

An error message is logged: “[IMAP]Message repeatedly failed to upload, this might indicate server incompatibility.”

Another message is displayed in the Operations dialog, which I can’t copy 'cos there’s no Copy to Clipboard option: “An attempt to connect to failed. This could be caused by temporary server unavailability or incorrect settings”

I was hoping to use emClient as my email client and would probably purchase a Pro licence as there are some excellent features and customisability there, but if it can’t handle anything other than my Inbox then it’s not much use.

There must be something wrong with my configuration, but as I’ve said, Thunderbird works fine with the same settings.

I’ve also checked my anti-virus software to make sure emClient is white-listed, so I’ve run out of ideas, hence this post :slight_smile:

You might give it some time. I was in a similar situation. They should have some indicator that the mailbox is synchronizing rather than just not seeing messages and slow response. I am using it with O365 and I left my Webmail open while I minimized my client for a while and let it run.
It has seemed to get better that my mailbox is sync’d.

Thanks, I’ll give that a go, but if a connection error occurs will emClient automatically retry or will it just give up?

I am new to emclient. I just installed today. It seemed to work better on the Mac I installed yesterday that the M$/PC I installed today.
There are settings in the client that you can set to sync every x minutes. It defaults to 10 minutes.
Top left > Menu > Settings > General > Synchronization

Yes, I have that setting at 10 minutes too. In the Diagnostics tab of the Account settings, it indicates that both IMAP and SMTP are working okay so I’m not sure why things aren’t working. I’ll leave emClient running for a while to see if it does download the emails in my other IMAP folders.


I’ve copied the mail server connection settings from Thunderbird into emClient, but no joy

What are your IMAP & SMTP setting. Blank out any personal info.

Here’s the IMAP settings, I can only post one screenshot as I’m a new user.

My ISP has advised that authentication isn’t required because I’m connecting via my ISP’s broadband.

Note that SMTP works just fine.


You would normally still use a “security policy” as well as the port eg: 143 / Use SSL/TLS if available.

Also have you tried the normal IMAP Port 993 / Use SSL/TLS on special (legacy) ?


I’ve just tried that and I get the same issue. The operations log shows “IMAP Synchronizing folder list” for what seems like quite a while but then fails about a minute later “[IMAP] MailClient.Accounts.ConnectionException: Courier-IMAP server shut down by signal”

What’s odd is that at some point up until 15th October 2021, emClient has managed to connect to IMAP and download my Inbox (the latest message is from 15th Oct), but now no matter what setting I used, IMAP just doesn’t work.

In contrast, Thunderbird just works, with the IMAP settings using port 993, with SSL/TLS security with authentication method as “Normal password”. Interestingly, if, in Thunderbird, I set connection security to STARTTLS it changes the port to 143; switching back to SSL/TLS switches the port back to 993, so Thunderbird just works.

What’s the equivalent of STARTTLS in emClient? Would it be Use SSL/TLS if available? I notice that when switching between that setting and use SSL/TLS on special port (legacy) it switches the port to 993, and when switching to Use SSL/TLS if available switches the port to 143

The problem is, when I contact my ISP, they quite reasonably say that if Thunderbird is working without issue, then it can’t be a problem at their end and must be an issue with emClient, which is not an unreasonable response.

I otherwise like emClient, but if it doesn’t work with my ISP’s IMAP, then it’s bye-bye from me.

Only other option might be to purchase a Pro license, get priority support and if emClient support can’t resolve it, then I invoke my 30-day money back and get a refund and move on.


MailClient.Accounts.ConnectionException: Courier-IMAP server shut down by signal”

This shutdown by signal error has happened for other eM Client users (with either port setup) where they had eg: Optional Antivirus programs installed scanning inbound mail & delaying mail getting into eM Client, or optional Firewalls / Security programs or VPNs installed interfering or blocking eM Client.

So if you have any optional programs installed like that try (completely disabling those to test).

If eM Client then works ok then you enable those one at a time till you find which program it is and adjust that program to allow eM Client to work.

Sometimes you have to eg: disable optional Antivirus (inbound mail scanning) or allow eM Client access through optional Firewalls / Security programs etc.

All my local ISPs using IMAP setup have always worked with port 993 , SSL/TLS on special port (legacy) so if you can suggest to stick to that.

Thanks @cyberzork, I’ve uninstalled all security software from my Win10 machine, only thing left is the built-in Windows security which I can’t uninstall and I’ve added the eM Client executable to the apps whitelist.

Settings are but I still get the same issue:

I’ve repaired the installation to no avail, I’ll try unisnatlling and reinstalling eM Client.

Are there any Windows 10 security settings I can tweak or disable?

Uninstalled and reinstalling eM Client, entered my ISP’s IMAP and SMTP server details…

Checked settings, IMAP port was set to port 143, security policy Use SSL/TLS if available, so switched that to Use SSL/TLS on special port (legacy) which automatically set the port to 993. Those are the recommended IMAP settings.

Saved the updated settings and retried getting all email, same issue again:

18:10:47 accountnameremoved IMAP Synchronizing folder list
18:11:03 accountnameremoved IMAP Synchronizing folder list
18:12:03 accountnameremoved [IMAP] MailClient.Accounts.ConnectionException: Courier-IMAP server shut down by signal.

When syncing I thought the icon (at end of red arrow) ‘twirls’ until finished

It did not. It would appear to spin when checking new messages but not reflecting sync.
Since sync completed it has worked okay.

So on my PC with no AV or security software installed, only the standard Windows Defender security active and with eM Client whitelisted in the firewall, I still get the issue. Most of my Inbox emails are downloaded but none of the custom IMAP folders have their contents downloaded (the folders are scanned okay, but they’re empty) and every time I hit refresh to get my emails, eM Client fails with the MailClient.Accounts.ConnectionException: Courier-IMAP server shut down by signal error.

I’ve installed it on my Windows 10 laptop (Surface Pro), still same issue, getting nowhere with eM Client so I’m not going to waste any more time with it and call it a day.

There are clearly issues with eM Client itself, as other IMAP clients (Thunderbird, Outlook) work fine. It works with GMail IMAP but with my ISP email, not a chance.

I’m wondering if the reason for the failures is that eM Client tries to do everything in one hit - I have quite a few folders each containing quite a few emails, so if eM is trying to download them all in one connected session, then my ISP IMAP server decides it’s connected for too long and terminates the connection? Maybe Thunderbird et al download all the emails over a number of sequential connections, thus avoiding getting kicked off the IMAP server?

Anyway, maybe I’ll try eM Client in years to come, but for now life’s too short and I’ve done more than enough messing around trying to get it working - and failing.

Big thank you to everyone who replied with info and advice on this thread, it’s much appreciated :smiley:


Looking at the support website the Courier-IMAP server shut down by signal error is a known issue with their mail server that is affecting many users and is under investigation.

Ps One guy on this thread has even tried 6 mail clients & same problems. See link below.

1 Like


Thinking about it, I should’ve googled that error msg :flushed:

So why does this affect eM Client but not Thunderbird? I might remove my PlusNet IMAP from TB, set it up to trace IMAP messages to see what’s going on when it downloads all the folders and emails.


So why does this affect eM Client but not Thunderbird

I have no idea how Thunderbird is not getting the same issues as appears to be mail server IMAP related from that community post.

I would let them know directly (via that thread or phone support) you are also having the same IMAP issues with eM Client. Their mail server guys need to fix this as is affecting alot of users.

1 Like

I have done via both that thread and by phone, though it’s been outstanding for months and still no eta on resolution.

Thanks again for all your help and advice.