Rideshare Cooperative uses two email servers, one that is integrated with the website, and another that is remotely deployed yet has privileges to send email on behalf of the Rideshare Cooperative domain, as indicated in ridesharecooperative.com's DNS records. Unless you are interacting directly with myself or another representative, all email is typically processed and sent from the remote server.
The remote server encrypts all messages with TLS 1.2, has been hardened to restrict compromised ciphers, and supports communication only with the highest email security standards common to the modern industry. The remote server is typically the one from which you will be receiving email.
Typically the issues are security and spam. Over the past year, popular email servers including Gmail and Yahoo! have been tightening security to protect their clients by validating SPF and DKIM and supporting DMARC, likewise supported by Rideshare Cooperative's remote email server. Yet unlike typical email server offerings, Microsoft appears to have implemented their own version of email security. Even email messages from a domain that has never been black-listed are summarily rejected by microsoft's email servers. They don't even end up in the spam folder, they simply do not show up, not in the recipient's inbox nor anywhere else, and no response indicates that a message was ever rejected by Microsoft's email servers. They are neither routed to an inbox nor spam folder, and other than evidence from the email-sending server logs that indicates the successful transfers of email, no traces exist at the recipient servers or in the addressees' email folders, as though the email messages never existed.
I have spent about a half year working through this issue with multiple teams at Microsoft and Outlook, and finally reached a point when Outlook's own tier-2 representative indicated that the 'powers that be at Outlook.com' are neglecting him as well regading this issue, and I was recommended by him to seek an alternate solution.
Knowledgeable people have asked me why I don't simply integrate or host my email on Microsoft's platform. True, I have been informed by Microsoft's representatives that email will not be prevented from reaching recipients if I were to integrate it with Microsoft's Azure cloud and/or Office platforms. In protecting your privacy I chose refrain from transmitting your data through third-party servers that will be able to mine it. Registrants who are concerned about privacy will typically avoid registering with email accounts that are hosted by services known to mine their data, and for their benefit the remote email server is not hosted on a third-party server, and the data that you enter into our website forms resides solely on Rideshare Cooperative's servers.
After consulting industry specialists it appears that the best option is to reject entries that include email addresses that are managed by Microsoft since their owners may never be reached. I encourage you to register for an email address from a different email service provider if you must do so to respond to the Driver Interest Form or to Rideshare Cooperative's mailing list.