Client Side Only standalone Smtp Client/relay, for sending mails directly

Question

Usually, when you send an e-mail (with Thunderbird or Outlook), you don't send it directly.
example: I have a gmail address and I want to send an e-mail to a myopera address. The process will be:

user->gmail server(gmail-smtp-in.l.google.com)->myopera server(in1.smtp.messagingengine.com)->final user who'll download it's email with pop/imap.
One of the inconvenient is the size: Imagine you have attachment of 50Mb: the limit of myopera is 60MB; but the limit of gmail is 25MB,So the mail will be refused whereas it would be accepted if it was send directly to myopera.

But I saw with telnet that, it is possible to send mail directly with SMTP commands.

I want to write a client-side Only web application which would convert a mail in a set of SMTP commands for sending it. I should be very basic and not support encryption

I don't know how to create a TCP connection from a client, so, here's my questions: Does a library already exist? If not, what I should use? I've read about the existence of WebSockets but that Ajax would be more universal.

Also, most of the actuals implementations of WebSocket I saw, don't work in my latests versions of web browser despite the fact they 'support it'. There's also the raw Socket API from the W3c (I've no idea of the web browsers which actually support it).
So, I would like to not avoid statements telling it is impossible to create near raw TCP/UDP session. Since it is possible, I can't imagine nobody created a kind of library for dealing with protocols

Answer 1

For Objective-C you may use https://github.com/jetseven/skpsmtpmessage

By looking at the source you see how SMTP works.

Answer 2

You should take an alternative route.

If i had that issue i would still use a server side component of some sort, and just have the server contact to receiving mail server directly.

Given the email: "[email protected]" you could do a DNS MX record lookup on "somedomain.tld" and find the receiving mail server say "mail.somedomain.tld", then you could tell your mail send component to send the email directly to "mail.somedomain.tld", that way you would have an immediate feedback on whatever the mail went through or not.