System.Net.Mail.MailMessage questions

Question

I am putting some email functionality into one of my asp.net projects:

I need to send an email to a list of subscribers, list varies from a few dozen to a few hundred subscribers - (down the road there could be thousands).

When I have a few dozen emails, I do this:

Mailmsg.Bcc.Add(New System.Net.Mail.MailAddress("[email protected]"))

for each subscriber, and it works fine.

What would be a practical limit on the number of email addresses you can add this way before you bogged something down? Also, if you add say 300 email address to a 'To' or 'BCC' field, where does the work happen that splits the single email into seperate emails? at your smtp server?

What are the pro's and con's of adding dozens or hundreds of addresses to you emails, versus having your code loop thru and send one at a time. Is one method more likely than another to be flagged as spam?

Answer 1

The limit is more driven by your connectivity and SMTP server...BUT, you are going about it the wrong way. One sure fire way to be seen as spam is to send an email with a bunch of BCC items. Send one email per recipient with them as the TO address and you will be better off.

Answer 2

A caveat for sending a bunch of emails with TO addresses, some SMTP servers will cut you off or limit your transmission rates base on how many emails you send during a 60 second time period, this is entirely dependent upon your email server or ISP.

Answer 3

BCC Cons:

Using BCC is not as blind as it's name implies. The BCC header is still attached to each message sent. This could mean you are compromising the privacy of the recipients by sharing their email addresses with tho other recipients. You shouldn't count on the receiving server stripping the BCC header.

System.Net.Mail

You are obviously not individually customizing the email messages. If you create the message and loop through your address list, I doubt your messages will take any longer to leave your SMTP server than the BCC method. Your .net code will take longer to execute, but I suspect the SMTP server will be the bottleneck. I am speaking without empirical evidence here, so please take this last bit with a grain of salt.