eM Client not properly synching gmail after Google security message

For my job I travel alot abroad and because of that -even though I have eM Client as an allowed app- I get a security message from Google every time I try to login at a different location.
The email does not get synched properly and when I compare it with my phone, when there are new messages they do not get synched. And even when I am back home and all the new messages get synched, the missed messages do not get resynched.
I use a different SMTP server for sending mail, so I can not use the standard Gmail settings in account settings, because I can’t add user name and password in SMTP settings.
Can anyone help me get this sorted?

Some providers will alert you when you login from a different location, or even from a different computer. Usually it is just an information message and you can simply ignore it. Don’t know why that would affect the messages not syncing. If you have a Pro License, you could open a support ticket with eM Client. I am sure they will be able to assist you with getting your business account working.

Hi Gary,

Thanks for your response. I just figured out the problems lies on the server side (i.e. Google). I installed Thunderbird to test it and it does exactly the same. It also skips a few mails on synching. Sadly I don’t know enough about imap and headers to figure out what the exact problem is and how to solve it, but at least the problem does not lie with eM Client.