SendGrid如何在未知我账户信息的情况下以我的邮箱发件？

Hey Dan, great question—this is a super common point of confusion when working with email service providers (ESPs) like SendGrid. Let’s break down exactly how this works, step by step:

1. The Difference Between "From" Address and Sending Server #

The From field in an email is just a label that tells recipients who the message appears to come from—it doesn’t mean the email was actually sent from your personal email server or account. SendGrid uses its own network of servers to deliver the message on behalf of the event organizer. Since you submitted your email to participate in the event, the organizer has explicit permission to use your address as the From value for invitation emails to your friend.

2. Authentication Protocols (SPF & DKIM) Make This Legitimate #

To ensure emails don’t get flagged as spam or phishing, the event organizer would have set up two critical authentication protocols with SendGrid:

• SPF (Sender Policy Framework): This is a DNS record on the organizer’s domain (or SendGrid’s shared domain) that lists which servers are allowed to send emails on behalf of that domain. When your friend’s email provider receives the message, it checks this record to confirm SendGrid’s servers are authorized to send emails even with your address in the From field.
• DKIM (DomainKeys Identified Mail): This adds a digital signature to the email. The recipient’s email provider verifies this signature using a public key stored in the organizer’s DNS records, proving the message wasn’t tampered with and was sent by an authorized party.

3. Permission Is the Foundation #

By submitting your email to the event and then providing your friend’s address for extra entry, you implicitly granted the organizer permission to use your email address in this way. This is a standard tactic in event marketing—emails from a known contact (you) are far more likely to be opened than generic event invites.

4. No Access to Your Account Required #

Crucially, SendGrid never needs your email account credentials (like your password) to do this. The entire process relies on domain-level authentication and the organizer’s permission to use your address, not accessing your personal email account directly. Your account remains completely secure.

内容的提问来源于stack exchange，提问作者DanT29