Yahoo mail uses port 995 for receiving email (POP), not sending (SMTP). That is port 465, but that requires SSL. The ethernet library does not have that capability.
And it requires a "Yahoo Mail Plus" account to use that port the last time I checked.
edit: I wait for a response from the email server after each of those sends. But that is just me.
530 5.7.0 Must issue a STARTTLS command first. fb20sm8661239wid.1
The Gmail email server is asking you to start your TLS. The ethernet library has no TLS capability.
You must determine the email server responsible for the receiver email domain and use port 25. If the server does not use an email filter like SpamHaus, you will be able to send to that domain only. SpamHaus is notorious for blocking residential ip address ranges.
I have my own email server on a commercial static ip account. It is easier that way.
I don't know. Have you tried sending that email directly to the hotmail email server on port 25? I don't know what you local hotmail server is, but you can find out with nslookup. From a command prompt:
nslookup
set query=mx
hotmail.com
It should give you a preference list and ips of your local hotmail email servers.
You should be able to use any of those. Try the top one. They usually rotate the same server ips over and over for a while. Every now and then, they replace one ip with another as they service their equipment.
Ready. Press 'e' to send
connected
220 BAY0-MC1-F23.Bay0.hotmail.com Sending unsolicited commercial or bulk e-mail to Microsoft's computer network is prohibited. Other restrictions are found at http://privacy.microsoft.com/en-us/anti-spam.mspx. Sat, 21 Jul 2012 12:31:48 -0700
250 BAY0-MC1-F23.Bay0.hotmail.com (3.15.0.97) Hello [95.159.97.9]
550 DY-001 (BAY0-MC1-F23) Unfortunately, messages from 95.159.97.9 weren't sent. Please contact your Internet service provider. You can tell them that Hotmail does not relay dynamically-assigned IP ranges. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors.
Remember what I told you about SpamHaus and blocking residential accounts? Well, your ip has been blocked by the hotmail email server as a dhcp account. That is why my email server is a commercial static ip account.