Add specific text in each cells of a selection directly, the following VBA macro.

excel

Step 1: Select the range in which you will add specified text;

Step 2: Hold down the Alt + F11 keys in Excel, and it opens the Microsoft Visual Basic for Applications window.

Step 3: Click Insert > Module, and paste the following VBA code in the Module Window.

Sub AppendToExistingOnRight()
Dim c as range
For each c in Selection
If c.value <> "" Then c.value = c.value & "@gmail.com" 
Next
End Sub

Step 4: Press the F5 key to run this macro.