i think the problem is straight forward and should be very simple to write a perl program for the same below is the program. i havent run it to check if it works fine. comments are welcome

1. Assuming table 1 having the address has a structure

address_tbl (mailaddress char(255))

2. Assuming table 2 having the count of domains has a structure

domain_count_tbl (domain char(255) count int)

@maillist query( select * from address_tbl )

for(i 0;i<scalar(@maillist;i++)
{
(name domain) split(/@/ myvar[i])
mylist[domain]++
}

foreach $key (keys mylist)
{
@res query( select 1 from domain_count_tbl where domain $key )
if (scalar(@res) 0 )
{
query(insert into domain_count_tbl values( $key mylist[$key]))
}
else
{
query(update domain_count_tbl set count mylist[$key] where domain $key )
}
}