07-19-2024, 08:34 PM
(07-09-2024, 11:50 PM)rlebeau Wrote: TIdSMTPRelay is an SMTP client similar to TIdSMTP, except that instead of connecting to a single SMTP server, it can connect to several servers.
TIdSMTP connects to 1 specified server and sends 1 email at a time, specifying all of the recipients of the email to that server. That server will receive the email and deliver it or relay it to other servers as needed.
TIdSMTPRelay, on the other hand, groups an email's recipients together by their domains, then does a DNS lookup on each domain to discover its registered SMTP server, and then connects to each server and delivers the email to only the recipients of that server.
Basically, TIdSMTP is what an end client would use, and TIdSMTPRelay is what a relaying server would use to forward emails to another server. Of course, nothing stops an end user from trying to use TIdSMTPRelay directly to bypss their own ISP, but they will likely be blocked by the receiving servers since they are not themselves a validated relay server.
Can you give me any pointers (or even code) as to where I start with this component?