Using SmtpClient.Send to send ~500-2500 emails what way would be faster.

Question

I'm needing to send around 500-2500 emails out at a time to internal email accounts. I'm wondering which was would be faster both for the mail server and for my client app. Should I send multiple emails with just different TO addresses, or just one with multiple BCC addresses? I tried testing this by sending a bunch to my own email and the multiple emails method work, but with the BCC and a single message I only get that single message in my inbox. Shouldn't I be getting as many copies as the number of times I put my address in the BCC line?

Answer 1

For the client of course, just 1 email with multiple recipients is faster.

For the server, it depends, if either method has an advantage, depending on the network layout/hierarchy. If this is a single server with multiple clients ...a single email with multiple recipients will have a slightly less overhead, since it will be a single task in which it will have to paste the same content at multiple locations, but copy the content only once(this again depends on implementation, but generally this is the true.)

If the network is multi-server multi-client network, then the original smtp receiver from the client will act as a sender to other servers or clients. In this case the single email has a definite upper hand. Since the content is only needed to be copied once per server recipient. This also reduces the overall All-server overhead.

So in both cases the single email method is better.