Can't add email account

[Barmouth]

Hi
I have a mid 2010 imac running High Sierra. I recently had problems with mail so I deleted the account (bt internet) and tried to add it again after changing my apple password. I have a total of three devices - imac, iphone and macbook pro.
When I fill in the starter box to add my account I get the message "unable to verify account name or password".
What is going on I really need my btinternet mail account and I was hoping one of you kind experts out there could help me get it back.
I am not a techy so simple english please. Thank you in anticipation.

 

[BrianBaughn]

First, you should remove that email address from your post. Web-crawling spambots will pick it up.

Second, have you verified that you can log in to the webmail portal for BT in a browser using the account name (full email address) and password?

 

[Yptcn]

When I had a problem with my @Myname email and couldn't add it again , the only thing that worked was rebooting my phone before adding it again.

 

[Quackers]

When I had a problem with my @Myname email and couldn't add it again , the only thing that worked was rebooting my phone before adding it again.

I had to do that too with just one of my email addresses.