Cannot get email to work

I'm totally new to this, although I have some limited DB/programming eperience.

I cannot get Akaunting to send emails. I am self-hosting (on Interserver), and I have tried my own emails on the same server and domain, as well as Gmail and nothing works.

I don't get any error messages just 'Invoice email has been sent', and there is nothing email related in the logs.

Is there an 'idiots' guide available anywhere?

I am on the verge of giving up on Akaunting, which is a shame, as it looks to be an otherwise excellent program.