The common mistake people do when creating operator for the first time or adding new email IDs in the Email-name list.
Below screenshots give over view on creating Operators in SQL Server.
1) Right click on Operators folder and click New Operator.
2) Provide name to the Operator.
3) Against E.mail name add the email list of people..main mistake done here is adding , between the emailIDs.
4) Separate emailIDs with ;( semicolon only). Adding , ( Comma) will fail sending notifications to all users added after it.