When sending an email windows Office 2019

When sending a multiple email what do you have to put between each address please, is a : and > or what? I have been trying to send a email BCC but it keeps being rejected and I am told Outlook will not accept the list of addresses I have used. What am I doing wrong please. As for the earlier problem about making a group address, I have sorted that one out.
Help Please?
RonBin87

RonBin87 said:

When sending a multiple email what do you have to put between each address please, is a : and > or what?

The standard divider is a semicolon ;

Thank you very much, saved me a lot of struggle.
Cheers,
RonBin87