My application will be used in a manner that the user is remote from his computer running the application, receiving data via text messages sent periodically from the PC. Im sending the text message via email, using the number#carrierdomain.com. To simplify determining the user's smtp server, I've been sending the message using the destination phone carrier's smtp, instead of the whatever may or may not be available at the PC. This has worked so far with AT&T and T-Mobile, but not Verizon, as they have discontinued their smtp service.
I'm using mailsend v1.15 http://www.muquit.com/muquit/software/mailsend/mailsend.html
but Im open to alternatives.
I do have a less than ideal workaround, which is to use google or hotmail's smtp, but that requires a login/pass.
If I can send the text through regular email, using outlook, it works. I've looked at outlooks smtp logs, but that doesn't really help.
If its not being sent to a Verizon smtp server, how does it get routed, and is it something that my application can use?
Is there a reliable way to send email without having the senders smtp?
Theoretically, any smtp server can send your e-mail. However, due to the overwhelming amount of spaming on the internet, pretty much every isp has locked down their smtp server and will not allow anonymous relaying of e-mail.
If you do have the outlook client on the box you are sending the e-mail you can look at using one of the Outlook APIs:
http://msdn.microsoft.com/en-us/library/gg608200.aspx
to send the e-mail message. You are using the outlook configuration then and don't have to worry about it your code.
As long as an SMTP server is configured to allow relay from a remote domain then you can use it send email from/to virtually any address. There are downsides, however, to using any SMTP server to send an email from a specific domain - the most notable of which is that the recipient's domain will likely flag the message as spam because the domain of the SMTP server is different from that of the sender's email address.
There are other non-email APIs that can be used to send text messages, if that is something you're willing to consider. Check out:
Tropo (http://www.tropo.com)
Zeep Mobile (http://www.zeepmobile.com)
Best of luck to you.
Impossible. SMTP is the Simple Mail Transfer Protocol, without this is impossible to access to another account with Email format. You can make a php mail where you don't need to have smtp, but your access will be limited, not all ESP / ISP will allow you to delivery those emails, because they need to identify you using your SMTP and MX Lookup (Reverse MX A records) from your server. It exists more ways, but are 100% SPAMMERS and HACKERS methods and I don't recommend to use them.
Related
I have a server on OVH and I'm trying to send some mail to my Gmail address using sendmail.
I installed sendmail with apt-get on debian, and echo "Subject: test" | /usr/sbin/sendmail -v mymail#gmail.com works. However Gmail puts the mail in the spam folder and says the mail is not authenticated.
I have no knowledge of how email works and from what I've seen I could use SPF or DKIM to provide authentication, but it seems it requires admin access to ovh DNS servers.
What would be the easiest way, using only admin access to the server that sends mails, to make sure emails sent from it are not marked as spam ?
Thanks
There are no easy way. That's the simple answer.
Google Mail is fighting spam every second, every day, all year. To get mail delivered directly to the inbox requires time and patience and there are no shortcuts. If there where, spammers would have it way to easy!
You are very correct that Google's SMTP servers will ask you to beef up your SMTP mail headers to include better authentication and security. There's no way around it if you want to be on good terms with Google's SMTP servers.
Here is a list of things to consider
SPF (Must have, also to defend spam sent in your name)
DKIM (Must have, this is somewhat a step up from SPF)
ESMTP (Google likes it when you talk to them encrypted)
Bulk headers (Use them if it's bulk, no reason to lie!)
Unsubscribe headers (Use them if you are sending out maillist content)
SMTP relay's with nice Senderscores (Easy access to the inbox, but cost)
SMTP relay's with good reputation (Easy access to the inbox, but cost)
Feedback loop headers/setup (If you send large amount of mails)
Only use "warmed up" SMTP relay servers (Mostly used by bulk senders)
Reverse DNS to match HELO/HELO (Mismatch can make problems)
Static IP (It's a given)
As you can see it's no simple task to "just" send an email to Google and expect it to be passed along to the users Inbox without getting targeted as spam.
Most of the options above requires extensive server knowlagde or that your hosting provider supports it. You need to have access to change your own DNS records but also the SMTP server that you send your mail from needs to be setup with the things in advance.
Now to the:
"How to send emails to Google Mail that always land in the inbox for dummies"
Well you basically buy your way into the inbox. Use SMTP services like Mailchimp, Amazon AWS-SMS (Simple Mail Service) many if not all of these services have already setup DKIM, SPF and are on good terms with Google. They do however have many rules and what and what not to do so if you don't follow the rules they will close your account right away.
When setting-up my mobile email client, I usually need to enter the SMTP relay server domain name, but why my email client need a SMTP relay server at all?
I think it can directly talk to the smtpd server (e.g. postfix) from which domain the destination Email address is, by looking up the DNS MX records. And send directly to it, why not?
Actually I have another confusion, if a smtpd server use SMTP AUTH, then how can a rely server elsewhere rely a mail to it? The rely server simply don't have the username and password necessary to transfer that mail.
Email clients use SMTP relay server to
simplify email sending (e.g. to avoid repeating delivery attempts by email client)
avoid being mistaken for spammers.
Direct email sending might be a reasonably simple option in ancient pre spam past.
SMTP AUTH is used (mainly) with email client to email server communication. SMTP server to SMTP server communication could not require SMTP AUTH without prohibiting email from "strangers". SMTP AUTH allows to accept messages from trusted clients (customers) even from IP addresses that otherwise would be blocked by DNSBL (e.g. DUL ranges).
A SMTP server these days does many more things:
Queues the emails and works on delivering them: this may not matter if you just send a single email here and there, but it's a different thing for a 500k recipients newsletter.
Retries messages than can not be delivered immediately (e.g., slow receiving server), and eventually bounces them if they cannot be delivered. According to RFC 5321 once a SMTP server accepts responsibility of an email message, it must not lose it but either deliver or return (bounce) it.
DKIM sign the message.
Route emails to go out from different sending IP addresses and host names, for deliverability purposes. (Email reputation is based a lot on sending IP addresses.)
Throttle delivery of large amounts of emails to avoid being seen as an aggressive sender and getting blocked.
Optionally, archive (or bcc) all outgoing email, for documentation or compliance purposes.
Of course you can also do all these things in your email sending application and then you don't need a SMTP server, then you wrote an SMTP server.
I am trying to build a mail server using Ubuntu to send mail
I have done some research on that and find it is nearly impossible for a individual to send
the mail e.g. hotmail , gmail.
The question i am asking is not how to build a own server, it is why i can not build my own server.
To be precise:
Questions:
1) what are the requirements to send to those e.g. hotmail ,gmail server ? e.g. mx record , clear dns record . (only from server aspect , not concerning other factors such as headers or mail content), It would be easier to understand if they are listed out.
2) I read some document and it said the problem can be overcome by relayhost, what is it about and is it feasible?
3) For those ISP , what are their procedure in building the mail server? How is it different from my own small Ubuntu one?
Sorry for asking a lot of question, any help would be nice and well appreciated .
Most people use an out-of-the-box package as a mail server, rather than trying to write one that follows all of the relevant RFC specifications for SMTP, Internet Message Format, IMAP4, POP3, etc.
I'm not saying "don't write your own", just that if you do, be prepared for months and months of hard work, lots of bugs and even more frustration. It's a big project.
In terms of sending messages, you will need to follow the Simple Mail Transfer Protocol (SMTP) to send messages; and they should be sent to the correct server, as per the recipient's DNS records - see RFC 1034 and RFC 1035.
If you are correctly using SMTP to send valid messages to the right server, there's not a lot else you can do.
Your next problem is going to be reputation. This would be the same, whichever software you use to send your messages.
It's easy for a spammer to set up a new mail server and start sending messages, so it will take a while for some mail servers to trust you (particularly those that are regularly targeted, such as Hotmail, Gmail, etc).
Instead of sending messages directly to the recipient's server, you can use SMTP to send the messages to a relay server. This would usually be your own ISP's server, but it can be any willing partner. You would normally need to make advance arrangements, so that they will permit you to relay messages.
The relay server would then attempt to send the message to the recipient server. If it cannot do so, it must report the failure to the sender.
Am developing and newsletter email software in vb.net for a friend, and he has asked me to add option to send email using dns servers,
How do i send an emai using dns server without smtp or imap?
Send email "using DNS servers" still uses SMTP. And it's generally a bad idea. Here's what it's about:
Usually, an email app (your own, Outlook, etc.) send mail using SMTP or similar protocol to a configured mail server. It could be a company's own server, or an ISP's server, or something like that. The mail may pass through various outgoing mail servers on its way out of an organisation, but at some point it hits a "boundary server" (There are pretty names for all these different types of server, but they're not important right now.)
This boundary server uses DNS to find the recipient's mail server and then sends the message (using SMTP) to that server. (I have omitted the details on purpose)
Sending email "using DNS" means that your app acts as a boundary server. It uses DNS to find the recipient's mail server and then sends the mail directly - rather than using any outgoing servers.
It's a bad idea for two reasons.
More and more ISPs block SMTP traffic that doesn't pass through their outgoing servers
More and more incoming servers validate the boundary server using various techniques. Your app is not likely to be accepted by these servers
Both of these issues are anti-spam countermeasures, so using this technique makes you look like a spammer, leaves many of your messages blocked, and is likely to get your IP address blacklisted.
Hopefully you can explain this to your friend so that they will understand that the "normal" way of sending mail is the only way to ensure that they don't get listed as a spammer.
For the past few weeks, I've been trying to learn about just how email works. I understand the process of a client receiving mail from a server using POP pretty well. I also understand how a client computer can use SMTP to ask an SMTP server to send a message. However, I'm still missing something...
The way I understand it, outgoing mail has to make three trips:
Client (gmail user using Thunderbird) to a server (Gmail)
First server (Gmail) to second server (Hotmail)
Second server (Hotmail) to second client (hotmail user using OS X Mail)
As I understand it, step one uses SMTP for the client to communicate. The client authenticates itself somehow (say, with USER and PASS), and then sends a message to the gmail server.
However, I don't understand how gmail server transfers the message to the hotmail server.
For step three, I'm pretty sure, the hotmail server uses POP to send the message to the hotmail client (using authentication, again).
So, the big question is: when I click send Mail sends my message to my gmail server, how does my gmail server forward the message to, say, a hotmail server so my friend can recieve it?
Thank you so much!
~Jason
Thanks, that's been helpful so far.
As I understand it, the first client sends the message to the first server using SMTP, often to an address such as smtp.mail.SOMESERVER.com on port 25 (usually).
Then, SOMESERVER uses SMTP again to send the message to RECEIVESERVER.com on port 25 (not smtp.mail.RECEIVESERVER.com or anything fancy).
Then, when the recipient asks RECEIVESERVER for its mail, using POP, s/he recieves the message... right?
Thanks again (especially to dr-jan),
Jason
The SMTP server at Gmail (which accepted the message from Thunderbird) will route the message to the final recipient.
It does this by using DNS to find the MX (mail exchanger) record for the domain name part of the destination email address (hotmail.com in this example). The DNS server will return an IP address which the message should be sent to. The server at the destination IP address will hopefully be running SMTP (on the standard port 25) so it can receive the incoming messages.
Once the message has been received by the hotmail server, it is stored until the appropriate user logs in and retrieves their messages using POP (or IMAP).
Jason - to answer your follow up...
Then, SOMESERVER uses SMTP again to send the message to RECEIVESERVER.com on port 25 (not smtp.mail.RECEIVESERVER.com or anything fancy).
That's correct - the domain name to send to is taken as everything after the '#' in the email address of the recipient. Often, RECEIVESERVER.com is an alias for something more specific, say something like incoming.RECEIVESERVER.com, (or, indeed, smtp.mail.RECEIVESERVER.com).
You can use nslookup to query your local DNS servers (this works in Linux and in a Windows cmd window):
nslookup
> set type=mx
> stackoverflow.com
Server: 158.155.25.16
Address: 158.155.25.16#53
Non-authoritative answer:
stackoverflow.com mail exchanger = 10 aspmx.l.google.com.
stackoverflow.com mail exchanger = 20 alt1.aspmx.l.google.com.
stackoverflow.com mail exchanger = 30 alt2.aspmx.l.google.com.
stackoverflow.com mail exchanger = 40 aspmx2.googlemail.com.
stackoverflow.com mail exchanger = 50 aspmx3.googlemail.com.
Authoritative answers can be found from:
aspmx.l.google.com internet address = 64.233.183.114
aspmx.l.google.com internet address = 64.233.183.27
>
This shows us that email to anyone at stackoverflow.com should be sent to one of the gmail servers shown above.
The Wikipedia article mentioned (http://en.wikipedia.org/wiki/Mx_record) discusses the priority numbers shown above (10, 20, ..., 50).
You're looking for the Mail Transfer Agent, Wikipedia has a nice article on the topic.
Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. An MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol.
The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.
You might also be interested to know why the GMail to HotMail link uses SMTP, just like your Thunderbird client. In other words, since your client can send email via SMTP, and it can use DNS to get the MX record for hotmail.com, why doesn't it just send it there directly, skipping gmail.com altogether?
There are a couple of reasons, some historical and some for security. In the original question, it was assumed that your Thunderbird client logs in with a user name and password. This is often not the case. SMTP doesn't actually require a login to send a mail. And SMTP has no way to tell who's really sending the mail. Thus, spam was born!
There are, unfortunately, still many SMTP servers out there that allow anyone and everyone to connect and send mail, trusting blindly that the sender is who they claim to be. These servers are called "open relays" and are routinely black-listed by smarter administrators of other mail servers, because of the spam they churn out.
Responsible SMTP server admins set up their server to accept mail for delivery only in special cases 1) the mail is coming from "its own" network, or 2) the mail is being sent to "its own" network, or 3) the user presents credentials that identifies him as a trusted sender. Case #1 is probably what happens when you send mail from work; your machine is on the trusted network, so you can send mail to anyone. A lot of corporate mail servers still don't require authentication, so you can impersonate anyone in your office. Fun! Case #2 is when someone sends you mail. And case #3 is probably what happens with your GMail example. You're not coming from a trusted network, you’re just out on the Internet with the spammers. But by using a password, you can prove to GMail that you are who you say you are.
The historical aspect is that in the old days, the link between gmail and hotmail was likely to be intermittent. By queuing your mail up at a local server, you could wash your hands of it, knowing that when a link was established, the local server could transfer your messages to the remote server, which would hold the message until the recipient's agent picked it up.
The first server will look at DNS for a MX record of Hotmail server. MX is a special record that defines a mail server for a certain domain. Knowing IP address of Hotmail server, GMail server will sent the message using SMTP protocol and will wait for an answer. If Hotmail server goes down, GMail server wiil try to resend the message (it will depend on server software configuration). If the process terminates ok, then ok, if not, GMail server will notify you that he wasn´t able to deliver the message.
If you really want to know how email works you could read the SMTP RFC or the POP3 RFC.
All emails are transferred using SMTP (or ESMTP).
The important thing to understand is that the when you send message to someguy#hotmail.com this message's destination is not his PC. The destination is someguy's inbox folder at hotmail.com server.
After the message arrives at it's destination. The user can check if he has any new messages on his account at hotmail server and retrieve them using POP3
Also it would be possible to send the message without using gmail server, by sending it directly from your PC to hotmail using SMTP.
Step 2 to 3 (i.e. Gmail to Hotmail) would normally happen through SMTP (or ESMTP - extended SMTP).
Hotmail doesn't send anything to a client via POP3. It's important to understand some of the nuances here. The client contacts Hotmail via POP3 and requests its mail. (i.e. the client initiates the discussion).