asp.net smtp mail queue - asp.net

does anyone know of a module thats available for asp.net that uses a queue to send email to an smtp server?
the queue being the operative word here.. we need a proper fallback mechanism for storing any messages that can't be sent so that the send can be re-attempted later
thanks

You can submit your messages to an IIS SMTP relay server via the Pickup Folder. This is the cheapest, and probably best, outgoing mail queue for ASP.NET.
Otherwise, you'll just need to connect to your SMTP relay server and configure its queue in whatever manner meets your business needs.

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How get the server ip in socket progrmming?

I want to create a chat application like telegram in qt quick.
I had tested the application with IP 127.0.0.1 and I send a message to the server and the server will receive the message.
Now if I deploy the application, there will be many clients and any client is the server for another client(If I understood correctly the socket programming).
So when a user wants to send a message to another user, He should have the IP of another user(that is server), So How can I solve the problem of having IP of another user?
I have a rest API(asp.net core) for signup users. Should I save the last IP of each user when he make a request in my asp.net core web api? and with get list of contact I send the last IP too?
Or there is a another way in socket progrmming?

Need not standard postfix configuration

The task turned out to raise the relay postfix, which can send messages from mynetworks, to attempts to send messages through it to the domain from other hosts, it
should issue 451. At the same time, NDR should be sent from it to the internal mail servers.
Please suggest how to implement it.
There were no problems with setting up opendkim, but there is not enough experience.

What are the main security considerations when opening up port 25 and/or 587 for email delivery?

I am about to setup SmarterMail v9.0 on our Windows 2008 server (IIS7) and would first like to know what some security considerations are when opening up port 25 and/or 587 - ie how to prevent relaying, etc.
Thank you.
You must not accept email from untrusted users/sources which is not bound for domains you control.
An open relay is a mail server which allows anyone on the Internet to email anyone else, without verifying that either the source or the destination is known - thus, a relay.
You can check that the source is known by looking for a trusted IP subnet, or by requiring authentication before mail can be sent (via LOGIN over TLS, GSSAPI [called "Integrated Windows Authentication" or whatever], X.509 client certs, or the like).
You can check that the destination is known by comparing it to the list of domains for which your mail server will be the "last stop" (or a relay to another domain you control).
Either a known source or a known destination should be sufficient, but you may also want to make sure that mail inbound for your domains is at least borderline valid (originates from a domain with an MX server, for instance).
Separately, you must be conscious of DoS issues (rate limit inbound mail), and the ability to use your server to send backscatter spam. Backscatter is when I connect to your mail server and say, "why yes, I am unsuspecting_target#not_my_domain.com, please queue up this message for not_an_address#yourdomain.com". Then your mail server delivers a "bounce" message to the unsuspecting target. To mitigate this, you can verify that the recipient is known before accepting mail, or limit the rate at which mail can be accepted from one host, or try to check that the host delivering a message is authorized to use that envelope sender.
These are all well-solved problems.

How to send Email through ASP.net using localhost

I am creating a banking application in asp.net v 2.0.I need to send confirmation email when a user creates the new account.
I am running the application in localhost.DO I need any special rights to send SMTP email?
provide me a proper way to send email from my application.
Regards
Jeyaganesh
Do you have a SMTP server set up on localhost? Test by using telnet on the server:
telnet 127.0.0.1 25
If the server responds, try sending raw SMTP commands to send an email and trouble-shoot from there.
I find the easiest way with the Microsoft SMTP server is to disable any checks for authentication and rely on relay restrictions, then restrict relaying to 127.0.0.1.
The fact that you're running on localhost shouldn't make any difference.
As long as you have valid email server settings, and it's allowed on the system you are running on, this works just fine.
Did you try it? Did you have a problem?
I think you can sent by gmail smtp server. check this out
http://csharpdotnetfreak.blogspot.com/2009/08/send-email-using-gmail-in-aspnet.html

Chat Application in ASP.NET

I've to write an Ajax chat web application in ASP.NET for a friend, and I've a question: if client1 sends a message to client2, how should the application send the message to client2? Is there a better way than sending requests to the server, "asking" if there are new messages? Is it possible to directly send the message to the client?
Best thing you can do is use a Persistent HTTP Connection. The way google does with Google Talk on their GMAIL website.
Remember that HTTP is a stateless protocol and that each transaction is made from the client to the server.
The server can use sessions to determine if this client is "known" but as for sending information back to the client using plain old HTTP I think that is impossible (I mean from a server initiated connection, not a response to the client)
You would need to use Javascript to poll the server for information.
If you want it the other way around, you could possibly use Java or Flash but then you also need to think about NAT tunneling, proxy servers and any other weird setups that the clients could be using.
No. I don't think the server can send message to client's browser.
Here is how I implement chat application:
client1 post message via Ajax to server
server save it to repository (I'm using singleton object for this case)
client2 get the message from repository
mark the message as read
I will save chat logs to database once the chat session closed or expired.

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