Write a linux script for data extraction from command output

Hi,
I need a bash script for automated processing of user quotas from dovecot.

This is what the script should be able to do:
run command "doveadm -f flow quota get -A".
The output is like this, but with @ instead of (at):
example(at)domain.de Quota name=user Type=STORAGE Value=xxxx Limit=xxxx %=74
dontcare-domain.de Quota name=user Type=STORAGE Value=xxxx Limit=xxxx %=23
unlimited(at)domain.de Quota name=user Type=STORAGE Value=error Limit=error %=error

Please pay attention to the three possible types of output lines. example(at)domain.de is a mailbox user with limited quota. dontcare-domain.de is an internal system user. unlimited(at)domain.de has no quota limit.
The script should care only about mailbox users like example(at)domain.de. You can use the fact that mailbox users have an @ in their email address and some number for the percentage to filter the mailbox users from the two other types.
For those, check if %=xx is greater than 70. If greater than 70, call another script with percent and user attached like this:
quota-warning.sh 71 example@domain.d

Conditions:
-Development takes place on your computer (no access to production server possible).
-Offer is binding. Increase of more than 30 % while developing is not accepted.
-Ask questions before sending an offer.