email come to Thunderbird in bursts about every 15 minutes. That has not changed for decades. THere are push notifications where certain email are "pushed out to Thunderbird by the server on receipt. But that is not very reliable as it can only push around 5 folders and that is not always the inbox that is one of them. Which folders are "pushed" is determined by the server not Thunderbird and those that use priority type inboxes on webmail tend to have issues with push notifications..

Thanks, not sure if the server is ntlworld or Thunderbird. If Thunderbird is the problem might need to look at another email provider as had not had these problems when using outlook.

There are some settings that affect that behavior. Look at menu item <Tools | Account Settings | Server Settings>. There are three check boxes:

[x] Check for new messages at startup [x] Check for new messages every (x) minutes [x] Allow immediate server notifications when new messages arrive

What are yours set as?

I have all three checked on all accounts, with the primary accounts set to check more often. I still usually receive new mail very soon or immediately when it arrives, although I find that Yahoo can be significantly slower than the others.

You can also manually check with F5 (current account) or Shift+F5 (all accounts).