Apart from Admidio which has already been mentioned, another option to explore is CiviCRM. Source: about 1 year ago

As a software developer, I looked at some of what they did, and some of what is commercially available for candidates. The guy who won in the races I ran in was spending $1500/month for a website that was a simple brochure. Something that could be set up for even folks running for school board might be a simple hosted brochure/blog site with Wordpress as a front-end, with CivCRM keeping track of volunteers and... Source: about 1 year ago

Https://civicrm.org/ [this works with a cms like drupal, wordpress, joomla etc]. Source: about 2 years ago

So far I found Chatwoot, CiviCRM, Corteza, ERPNext, EspoCRM, Dolibarr, Odoo, OroCRM, Mautic, SuiteCRM and X2CRM and there are probably even much more available. It seems that Odoo and ERPNext are huge but also very flexible (with many extensions available). Source: over 2 years ago

If you are already using wordpress, you may also want to look at CiviCRM [https://civicrm.org/] for managing members etc. It is used by non-profit orgs. Source: over 2 years ago

USPS isn't the only address validation. In fact, many businesses use Melissa. Check your address on USPS.com and also on melissa.com. If melissa doesn't have your address, you can submit a "suggestion" and hopefully they'll get that fixed for you. If it's USPS that doesn't recognize your address, then (I believe) your carrier has to correct it in his route book and then (eventually) it'll work it's way to usps.com. Source: over 2 years ago