Why do emails get stuck in Apple Mail outbox?

I cannot always receive emails on my MacBook Air, it is up to date with latest OS 15.0.1 I have no problem with outlook on my Mac air, it is the apple app that seems stuck. also why do emails get stuck in apple mail outbox, I have no problems with iPad, or even iPhone it is just the Mac book air.

I do not want to use outlook all the time as I find it clunky compared to the clean lines of the apple mail app, but it does not seem to sync lately I am using iCloud on all devices.

I now nothing of Imap or any other, push pull etc...

any help would be appreciated.

mike

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