Need to concatenate cells but limit number of characters from each original cell

Trying to save time creating new email addresses by combining cells containing first name last name and a number.  Trying to do this using the concatenate function but can't work out how to limit the number of characters taken from each cell to 3 characters. E.g if 3 different cells contain data: Josephine, Bloggs, 44449587.  I need to take the first 3 letters of names (Jos,Blo) and the last 3 digits of the number (587) and combine to form an email address: josblo587@example.org.uk and repeat for a large data set.

It would speed up my work ridiculously if i could sort this out, thank you