SMTP question

[DJFuji]

quick question:

I've been accessing and sending POP mail for years by specifying the POP3 and SMTP server in my mail program as "mail.domain.com", where domain.com was one of the domains i owned.

For some reason, i never did send through my ISPs SMTP server. Anyway, I recently talked to some "tech" from a dialup ISP that claimed that the ONLY way you could ever send mail, broadband or dialup, was by specifying the ISPs SMTP server.

I told him that i'd been using "mail.domain.com" for my domains for years now, so how could that be? He mumbled something about "that's impossible," and that "well your domain host must be a POS then, because all the GOOD ones don't do that."

My broadband connection and even my past dial up connections have worked fine with the domain SMTP setup, though recently my Dad's ISP seemed to block all SMTP server's but their own. Is this a common occurrence?

Further, is there any advantage to using an ISPs SMTP server instead of my domain's? Thanks.

 

[n0cmonkey]

Wrong forum.

Your ISP isn't blocking it, your smtp host isn't denying you relaying.
Do you have to authenticate for SMTP?
Many ISPs block port 25 outgoing.
Advantages? Maybe, depends on the quality of each server.

 

[Jugernot]

Yes, it's common for ISPs to block all SMTP traffic others than through their server. They do this so they can control what mail is being sent from their network. If you can use your own SMTP server, you can send spam from their network, which is bad. 🙂

Joe

 

[Descartes]

Cox filters port 25 outgoing, in my area at least. It's a real pain in the arse for me, because it won't even let me change the reply-to when sending emails for work from home.

 

[GeekDrew]

I use insight roadrunner as my ISP... I have to use the smtp.insight.rr.com mail server for SMTP... UNLESS I authenticate to another SMTP server... if I authenticate I can send on other servers. If I don't authenticate, I have to only use my ISP's mail server.

 

[DJFuji]

Originally posted by: GeekDrew
I use insight roadrunner as my ISP... I have to use the smtp.insight.rr.com mail server for SMTP... UNLESS I authenticate to another SMTP server... if I authenticate I can send on other servers. If I don't authenticate, I have to only use my ISP's mail server.

That's been my experience as well through adelphia. Just threw me off when the guy said it was impossible. To clarify, though, does that mean my computer sends mail by relaying it to mail.domain.com through port 25?

Descartes, can't you just create another mail account in outlook with your "name" and "email address" corresponding to your work information? I've been playing around with things and realized that I can create all sorts of bogus information in outlook and as long as the "logon" information is correct and i have an SMTP server specified, i can send the mail. For example, i can say my name is "bill gates" with the address "bill.gates@microsoft.com" and my ISP will still send it. Is this supposed to happen?

 

[GeekDrew]

Originally posted by: DJ Fuji

Originally posted by: GeekDrew I use insight roadrunner as my ISP... I have to use the smtp.insight.rr.com mail server for SMTP... UNLESS I authenticate to another SMTP server... if I authenticate I can send on other servers. If I don't authenticate, I have to only use my ISP's mail server.

That's been my experience as well through adelphia. Just threw me off when the guy said it was impossible. To clarify, though, does that mean my computer sends mail by relaying it to mail.domain.com through port 25? Descartes, can't you just create another mail account in outlook with your "name" and "email address" corresponding to your work information? I've been playing around with things and realized that I can create all sorts of bogus information in outlook and as long as the "logon" information is correct and i have an SMTP server specified, i can send the mail. For example, i can say my name is "bill gates" with the address "bill.gates@microsoft.com" and my ISP will still send it. Is this supposed to happen?

Your computer doesn't relay mail (unless you're running an open mail server, in which case you would know). Your computer attempts to contact the SMTP server you specify, using port 25. Your ISP has the ability to block all traffic on port 25, to block traffic not going to their own servers, or to permit all traffic. Most ISPs chose some form of the second option.

You can create whatever account you want, with whatever name and e-mail address that you want. Whether it goes anywhere or not is up to your ISP. In your above example, you could send a message saying that you are bill gates, using the above microsoft e-mail address, and it could either be sent by your ISP's mail servers, or it could be rejected. Some ISPs base whether or not to send mail on the return address; if it is outside of their domain, they drop the message. Some ISPs ask for authentication when sending: it refuses all messages that are attempted to be sent through it without first authenticating.Some ISPs permit sending without verification, if your origin address is within their domain (or they otherwise determine that you are on their network). Any way you go, they can determine where the message originally came from (what machine or user). And finally, some ISPs permit mail to be sent from anyone, to anyone. That is said to be acting as an open relay - which usually means you are blacklisted, and most domains will reject any mail from your servers. Why? Spammers use open relays to send their mail.

Drew