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Send mail with not existing mailaccount as sender

I'm currently facing an obscure problem and I hope that someone might know an answer to this.
In the past, my company was working with Delphi 5. Email-sending was handled by a component called TNMSMTP. It's custom for these applications to use fake mail-adresses as an additional source of information. For example, if the service "ReceiveDelivery" on the server sv102 would encounter a problem, the mail adress would be ReceiveDelivery#sv102
I'm rather new here and try to convince management to make the step to .net programming. For that, I need to imitate the above behaviour by using the system.net.mail framework.
However, whenever I try to use a fake mail address I receive the 5.7.1 "Client does not have permissions to send as this sender" exception.
The new Program runs on the same server, under the same user and tries to access the same smtp server as the old delphi programs.
My question is: Can I somehow bypass this, or do I need to get back to Delphi for this to work?

The error you're receiving is from your smtp server, which indicates that you're not authenticating with the server in the same way as before.
Are you sure you've correctly configured the smtp client? You can do so using the smtp configuration element in your .config file or at runtime programmatically.
Also, you could try using the fully qualified domain name (FQDN) of the server. For example the sender email address would be: ReceiveDelivery#sv102.internal.company.com. You can get the FQDN using the following .NET code: How to find FQDN of local machine in C#/.NET ?.

so we finally found the solution to this problem.
It seems that the right to send mails with variable sender adresses is not bound to specific users, but to the server the application is run on.
In my case, the .net development server wasn't in that list. Now that we added it, I can use this functionality.
Thank you guys!

Email Anonymization Similar to Craigslist in C#

I am developing a site for which I would like to protect buyers by anonymizing their email addresses.Similar to craigslist's system, when a seller needs to contact a buyer they should be able to send an email to an anonymized address such as 1425415125#mysite.com which will then be routed to the user's email address.
My plan right now is to:
Set up a bucket (catch-all) inbox
Generate a random key for each buyer which will be the user specific ('1425415125' above) section of the email address
Monitor the bucket inbox and parse out this user specific section. Once I know the user, the email can be forwarded to the correct address
My questions are as follows:
Can you see any issues with the above solution
Are there any open source solutions to the existing problem
Are there any gotchas that one should be aware of when developing such a system?
Thanks in advance
JP

I did something related, though not quite the same. I setup a catch all inbox on my existing pop3 server (you probably have one already I'm guessing). I then used OpenPop.NET to read all new messages on a timer (say every 30 seconds). In my case I stopped at just processing the messagse but it's easy enough to generate a new message to the appropriate address and copy the body over, then send the new message out on your SMTP server.
One problem I see with your setup, and maybe it's just a misunderstanding on my part, is that while you are protecting the users original email address they will continue to be reachable at 1425415125#mysite.com basically forever. If I understand the way craigslist works, each posting has a different email address, and once the posting has been deleted/removed (or shortly after) the email address stops working. This makes it so that people can't just keep bugging you on that email address. The solution to this issue is easy, just make the email address coorespond to a post id or some other id rather then the users id in the database. The lookup will be just as quick but they will have a new email address each time.

You may wish to look at mail "piping" - the ability for someone to send an email to a mail server, which then gets thrown immediately to an executable, which then forwards your mail onto the recipient (by pulling the real email address from the database based on the incoming address from the piped message).
My personal recommendation would be to check out HMailServer, which has a COM API (the admin side is written in PHP, hence the requirement for legacy interop), is free and open-source, and is very well-documented. It doesn't have mail piping built-in, but is easily extensible given the API and support for scripts which run on server-side message events
HTH,
Benjamin

I think this solution will make sense and is in use in a lot of cases. The hardest part is actually receiving the messages. You can actually handle all of this within your web app if you need to. I wrote a blog post highlighting a couple of ways to receive email in your web app. It applies mainly to Rails but the concepts should be transferable.

The way you are lookimg to do it is the way I created a similar service. I would not recommend you writing your own smtp server. Use an existing mailserver and just use polling or some event based api.
The benefits of using a 3rd party mailserver is you can use existing backup and management tools on it.
Edit: I just noticed this has beed answered here with a better explanation. Pipe incoming email to a script on Windows IIS SMTP?

I do not see any problem with your setup, infact that is correct way to do because if your scheduled application fails, the emails will still be in the catch-all email box. Only once the email has been successfully delivered to somebody, the email should be deleted. You will be able to monitor and log the activity of your own application to monitor progress and failures.
I do not recommend Piping because, if for any reason piping goes successfully but your exe crashes, you will loose the email. Tracking will be difficult. Scheduling the jobs will not be possible.
If your application is independent of mail server, it is easy to manage it and replace your mail server whenever possible. It is easy to extend.
In this you will have to use some pop reader library, and schedule your application to run frequently.

In addition to email, you may consider a pull rather than push delivery mechanism, e.g: a message center web frontend or RSS feed. I say this because deliverability problems to various ISPs can be very difficult to troubleshoot and in my experience your users will never believe it's their ISP.

send email via asp.net 3.5

Im looking to send email vi a .net 3.5 form (C#)
Ive seen a few posts elsewhere and got the thing running ok for certain addresses but not for others, eg gmail accounts.
The finished app will have to pick up addresses from a database so Im having to cater for a lot of possibilites.
Im not looking to have my work done for me, just a shove in the right direction would be cool!
thanks
DD

Is it possible the gmail accounts are blocking you as a spammer? If you're sending out a lot of emails, or if there is a configuraiton issue on your server, they may have blacklisted you.
If the emails are going out from your server OK, but not reaching ALL of the recipients but is reaching SOME, then there is likely an issue outside of your direct control. An email goes through several servers in between your server and the enduser's inbox (and that's the case even if the inbox is on google's server for gmail.)
That said, there are things you can do to reduce your likelihood of being blocked/blacklisted.
This is a good place to start: http://www.andreas-kraus.net/blog/tips-for-avoiding-spam-filters-with-systemnetmail/
and then here is where to go from there. (Sorry - it's just a google search, but I gave you the relevant terms, at least.) http://www.google.com/search?q=system.net.mail+blacklist+spammer&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1
Finally, here's a very good resource with a cool URL. Perhaps the force will be with you if you learn these ways, young padawan.
http://www.emaildeliveryjedi.com/avoid-spam-filters.php
But getting back to your original question - everything you need to know about how to write code to send an email is covered here: http://www.systemnetmail.com/ It's the same for all versions of .NET from 2.0 on uo through the current 4.0.
And I'm sure you're already aware, but in case you're not, be sure you're familiar with the CAN-SPAM act. http://business.ftc.gov/documents/bus61-can-spam-act-compliance-guide-business

In addition to the great info from David Stratton...If you're certain that the gmail accounts are not receiving your emails, i.e. you've waited for sometime, checked the gmail spam boxes, and you've checked your SMTP server logs to ensure that Google is not sending any particular messages back to your SMTP server, then you may have run into a case of grey-listing / black-listing.
Black-listing can occur when a mail service has decided that the IP address of your mail server is a spamming server. It can happen under different scenarios, shared scenarios can be quite common.
One shared scenario: Let's say you recently acquired a new IP address, but it was recycled by your hosting provider from a prior client of theirs, who was a spammer. There is no guarantee that the IP address would be white-listed.
Another shared scenario: You're sending emails on a shared hosting website, where your SMTP service that you are using is shared with other clients of the SMTP service provider. It may be that one of those clients used the SMTP service maliciously or without following appropriate SPAM rules that gmail abides by.
Your best bet is to contact Google to commence a white-listing process. Providing you follow their requirements, they should eventually unblock emails originating from your service.

Sending Email to a specific address without requiring user to specify their mail server details

Can anyone recommend a simple and reliable method of sending email notifications and possibly log files attachments from a C# program without requiring the installer or the user to configure the program by specifying server details and email addresses etc.
(Mainly because they won't know the details, but also because they could change)
The program will normally be run as a service of a Windows Server, but can be run on a client.
I tried connecting to our own mail server and sending a email to myself, but some ISP's are blocking Port 25 on all servers but their own, so that method isn't working reliably.
Tried sending email through gmail but that was less successful as the port they used was blocked by firewalls. Ditto webservices connecting on weird ports.
Trying to use the local smptservice but did not work either.
It would be nice, but not essential if it was not dependant on my own Internet connection/Servers. (Don't mind them being delayed, but prefer them not to get lost).
Are there any webservices on http/https that allow you to do this sort of thing?
TIA

try using cdosys
http://support.microsoft.com/kb/310212
http://www.eggheadcafe.com/articles/20030316.asp

May have discovered the solution.
Was catching up on my blog reading over the weekend and came across a recent entry on Coding Horror and the very first comment mentions PostMarkApp which seems to do everything I need (and almost everything I want, apart from attachments which they are considering).

C#: Safely send bug report from a program

I would like my program to email me a bug-report when it fails. Is there any way of doing this... safely? I have found I can use System.Net.Mail MailMessage and SmtpClient and such, but of course, I will have to provide a username and a password to it (unless someone knows of one that doesn't need it?). And putting that in code I find a bit... I don't know. Technically it would mean that anyone could look at the source code or the compiled IL code (or what it was called) and find that username and password and use it for spamming or other not so good activites. Which is not very good!
Any ideas? Is there a better and/or different approach to this problem? Doesn't really have to be through email. But what I want is a way for the program to notify when something happens that I should fix. And to make that notification as little troublesome as possible to the user. Maybe even invisible (although a YesNo messagebox might be polite).
Anyone?

Instead of sending mail you could set up a web service that would receive the reports. The web service could run over https if you want to protect the data.
I did this for a customer once and it worked well.
The only problem is if the program is running somewhere without internet access.
Edit:
Don't tell this to anyone, but we even took a screenshot of the program when it crashed and posted it together with all information about the error that we could gather. It was incredibly useful!

You don't need to provide your password to email to yourself, as you don't need other people's password to send email to them.
You only need a password if you relay an email over a third party's SMTP server.
If your SMTP client connects right to example.com on port 25 and sends an email to test#example.com, no password is needed.
example.com above means an MX record, not an A record. This is a special type of record that holds the name of the server where all emails for example.com should go. There is no easy way to look it up from .NET, but if you are not going to change your SMTP server's address, you may hardcode it into SmtpClient.Host property.
To find out your mail server's address, type nslookup -q=MX example.com at your command prompt.
SMTP is not the best way to report errors, though. Home providers often block traffic on port 25 to all servers but their, to prevent spamming etc.
You better make a web server, create an instance of System.Net.WebClient in your program and send bug reports over HTTP. It's more reliable and you can easily use your client's proxy settings.

You can put the username & password in a web.config/app.config file. You can also encrypt the contents of your .config file (see here).

I do the same sort of thing and when our mail server moves to require authenticated SMTP, we plan to add exceptions for mail from certain addresses so that our automated processes don't need to provide credentials. If you're stuck with authenticated SMTP you'll need to work with your mail service provider to set up the same sort of exception or supply your credentials.