When you send a newsletter to 3000 addresses, then you have 3000 chances of being reported to your ISP as spammer. Most people won't bother reporting you and some will just tell their own spamfilter to blacklist you. Buy if 1 in 1000 will report, then your ISP will receive 3 reports of abuse and your account could be terminated!
There is no limitation but whatever you're programming that should send those emails must make sure all recipients are added to the BCC section, not the from or CC section of the email. Otherwise, those people will also receive a lot of addresses from other people who received your mailing, thus increasing the chance of you being reported.
You will also need explicit permission from all those people showing that they've opted in for this mailing list. Your friend should show you evidence of this, else you better just refuse this. This permission is required to tell your ISP that the recipients have requested the mailing, thus you're not spamming.
There are several programming options to send email and many use their own build-in SMTP server. I wouldn't expect many problems here. The only limitation you have are the ones provided by the email provider who'se services you will be using to send those emails. With IIS you're most likely going to use the provider who also provides your Internet connection. Piss them off and you're kicked from the Internet. Thus, better piss off another provider. ;-)
Be aware that even a single email could be considered spam. Make the intentions of this email extremely clear and make sure the contents is readable with and without HTML markup. Add an unsubscribe button or provide options for the recipients to unsubscribe themselves some other way. And once you've sent them, be prepared to receive some heat because of it.
Btw, I'm not a lawyer, but contact a lawyer to be sure about possible legal consequences if this goes wrong!