Working on Putting Together Email Addresses

My coding club has a spreadsheet of student accounts. Each account needs me to make an individual email address. Fortunately, they all follow the same pattern

firstname.lastname@ymca.ca

The first formula I tried was TEXTJOIN. 

This formula =TEXTJOIN(".",TRUE,A141,B141,"@ymca.ca"), gave me the following.

Firstname.Lastname.@ymca.ca

Then I needed to change the capital letters to lowercase, so I used the LOWER function, =LOWER(I139), which gave me

firstname.lastname.@ymca.ca

Looking for a way to remove the period after "lastname", I tried the SUBSTITUTE function, =SUBSTITUTE(I140," ","."), which gave me the following result.

firstname lastname @ymca.ca

Frustrated, I Googled the answer.

SOLUTION

The CONCAT function.

Solution Page