I'm pretty bad at such stuff, but if you have the command to increase the mailbox size, a simple loop in a bash shell script would likely be fine. Put your email addresses in a file, 1 line per address/account (this example uses /tmp/users/accts), and then something like this:
# begin loop to add the requirements to each acct in this file
for i in `cat /tmp/users_accts`
user_name=`echo $i | grep -o '^[^@]\+'`
echo "email address is $i and username is $user_name"
echo "increasing mailbox quota for this account...."
zmprov ma $i ZimbraMailQuota PUT_YOUR_NUMBER_HERE
echo "Done, moving to the next acct"