Thunderbird setup doesn't work well

Thunderbird setup doesn't work well

Hello, I just moved to Zoho Mail from my old provider because of some problems with Yahoo addresses and poor customer support I was having. I have sticked with the free plan for now.
I verified my domain ( delmarauto.ro ), updated my MX and tested everything from the Webmail interface. Sending / receiving works perfectly, even though some mails take a long time to send (30 sec, unusual?). I enabled SMTP and IMAP for this account in my admin console.
I am pleased with the webmail performance but I am unable to get it work on Thunderbird. Is is a problem for new accounts? Do I have to wait?

I am trying to setup in Thunderbird and I am getting lots of errors: first it says it can not detect my settings, if I press the retest button more times it says incorrect password, and after I finally get it to add in the account list, it downloads the email but I can not see the content. Just the subject and thunderbird tells me it can not contact my IMAP server. Sending works in thunderbird (mails are sent but copying to the sent folder stays for some minutes after each sending).

I am sticking with your service for now and willing to upgrade, but this is kind of a major problem. Ideas? 
PS: Happens on Thunderbird on multiple PCs. All of mine. Will this get solved?