# Fresh Install and a some questions on unique identifiers **URL:** \ **Category:** General Discussion\ **Created:** [May 9, 2024, 5:55am UTC](https://forum.mautic.org/t/fresh-install-and-a-some-questions-on-unique-identifiers/32016 "2024-05-09T05:55:25Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![jeffg](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.mautic.org/jeffg/32/13468_2.png) [@jeffg](https://forum.mautic.org/u/jeffg)\ **Post date:** [May 9, 2024, 5:55am UTC](https://forum.mautic.org/t/fresh-install-and-a-some-questions-on-unique-identifiers/32016/1 "2024-05-09T05:55:25Z")
I have been using Mautic on Microsoft Server connected to Amazon SES for a few weeks. The original install was a pain but I hacked my way through. Beginning 4/24 I started ramping up and I’m at 12-15k per day, with a total so far of 75k sent. At the same time I am almost finished importing the email database of about 200k addresses. There were about 1 million records and I brought them in chronologically and Mautic did a nice job of updating the records with current data. My campaigns are set up to run about 3 weeks. The first segments I set up were based off of cities and I used the major ones in a given area. Now I want to pull in contacts in that area but I don’t want to have a million city filters so I was planning on using a zip code prefix which will be close enough. Some of these segments will overlap, as in a contact may be a member of both segments. If I add the zip code segment to the existing campaign and city segment - will this result in a double send? Next question is what are the primary key or unique identifier for a contact? What can I include in an update or import that will guarantee I don’t duplicate a contact record? Last, I pulled in my records with state abbreviated. I have read where some others had this issue but I never saw how it was resolved. Can I just update a table and be done with it?