Email Address Varification Application in ASP.NET - asp.net

I am getting 555 syntax error in mailfrom
SendData(tcpSocket, string.Format("MAIL From: {0}\r\n", MailFrom));
if (!CheckResponse(tcpSocket, 220))
{
tcpSocket.Close();
return false;
}
is it the problem in my local system because of localhost?
Please help me. I am using this code from below link.
http://www.codeproject.com/Articles/5189/End-to-end-Email-Address-Verification-for-Applicat

Please don't try to implement your own SMTP client, use the one that comes with .NET: System.Net.Mail.SmtpClient.
Many SMTP servers require TLS, for example, which your code does not account for.
Furthermore, for security reasons most mailservers will not reveal if an email address in an RCPT TO line is valid or not. If a system can positively reveal an address exists then it can be used by spam harvesters. Consequently using a dry-run of an SMTP client should only be used to validate an email address (because of the complicated rules regarding valid email addresses). The verification (a separate concept from validation) must be performed manually by requiring the user to respond to an email sent to that address, there is no other way to be sure.

Related

How to set hostname used in JavaMail or Apache James Message-Id header?

I am having issues with mail bouncing when sending from my own server to my own active yahoo account using JavaMail. The mails are passing SPF, DKIM and DMARC according to google mail that receives the same messages being bounced by yahoo. I can send messages from other accounts to my yahoo account without issue.
The messages send fine from my server to ZMail, GMail, Microsoft mail. Looking at the emails, the only thing that I have noticed is the message header for the Message-Id. My messages have the following header:
Message-ID: <923936395.17.1634776639078#[internally visible hostname]>
I am wondering if this header could be the problem and whether there is a way in JavaMail or in the Apache James to set the hostname or IP address that gets used in this message so that rather than using the "internally visible hostname", I can get the hostname that is externally visible. I have been searching the available documentation for Apache James and JavaMail but have not found any parameters to try in order to resolve this.
According to the Decompiled SRC of sun mail it should be possible by setting some properties for your session.
props.setProperty("mail.from", user);
props.setProperty("mail.host", host);
//props.setProperty("mail.user", user);
The Id will be updated by the save method (saveChanges()) and will trigger an new ID generation (updateHeaders() -> updateMessageID()). (Looked up in the decompiled MimeMessage.class)
Leading to the HostPart called in javax.mail.internet.InternetAddress.
The relevant method is _getLocalAddress.
Here you can see that the values get extracted from the Properties or will fallback to your local machine.
Used Fields:
user.name
mail.from
mail.user
mail.host
The user.name property can also be looked up from the system props.

Error Sending mail through Gmail SMTP relay [duplicate]

This question already has answers here:
Sending email in .NET through Gmail
(26 answers)
Closed 2 years ago.
I'm working on building a contact form for my new Web site and want to send mail through Google's SMTP relay server (smtp-relay.gmail.com) because I want to set up a "dummy", "no-reply" address from which to send the mail. Also, I tried sending it through the regular SMTP server (smtp.gmail.com) using my own actual Gmail credentials for that account and it got blocked as an insecure app. I'd rather not turn on the "Less secure app access" option (it's not really an option for me anyway because I use 2FA on this account), so this seems like the best way to get there - if I can get it working.
The domain's mail is hosted in G Suite and I've configured the SMTP relay service in the Google Admin Console for my domain as per the instructions in the support article, SMTP relay: Route outgoing non-Gmail messages through Google. I have the relay configured using both the public static IP address of my Web site, as well as the static IP address of the firewall behind which the Web server lies. I configured the relay to accept mail from my domain(s) to allow for the "dummy" address that doesn't actually have a mailbox, and set it to require SMTP Authentication and TLS encryption:
I've set up DNS records for MX, SPF, and DKIM with my domain registrar.
I've waited over 24-hours for the changes to take effect (as per the notification when making the changes in the Google Admin Console)
I've even set up an app password for my Web site to use for my domain e-mail address:
I'm using an ASP.NET (VB) Web site on IIS. My code for sending looks like this:
Dim NewContact As New System.Net.Mail.MailMessage()
With NewContactMessage
.From = New System.Net.Mail.MailAddress("no-reply#mydomain.com")
.To.Add("myaddress#mydomain.com")
.Subject= "TEST MESSAGE"
.IsBodyHtml= True
.BodyEncoding = System.Text.Encoding.UTF8
.Body = "This is a test."
.Priority = System.Net.Mail.MailPriority.Normal
End With
Dim Server As New System.Net.Mail.SmtpClient()
With Server
.Port= 587
.Host= "smtp-relay.gmail.com"
.EnableSsl= True
.Send(NewContactMessage)
End With
However, when I try to submit my contact form, I get an error, Mailbox unavailable. The server response was: 5.7.1 Invalid credentials for relay [X.X.X.X]. The IP address you've:
It looks like there should definitely be more to that actual error message, but it's apparently being truncated somewhere along the way.
I've tried feeding the credentials in the SmtpClient block:
With Server
.Credentials = New System.Net.NetworkCredential("myaddress#mydomain.com", "my_app_password")
.Port= 587
.Host= "smtp-relay.gmail.com"
.EnableSsl= True
.Send(NewContactMessage)
End With
In this case, I get a different error: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication Required. Learn more at. (If I use the credentials with the "default" Gmail SMTP server (smtp.gmail.com), I get the same error.)
According to the Audit Logs, it appears that all of my configuration setting changes have completed. Everything appears to be correct for this to work, but what am I missing?
Just before posting this question, I found this Q&A - Send mail via google app with smtp relay - with the simple fix to my issue: Turn off the Require SMTP Authentication option in the SMTP relay service configuration settings.
Once I disabled that setting and tried again, everything is flowing normally. I suppose I should have figured that out on my own, but according to Google's support article for setting up the SMTP relay (emphasis mine in the first sentence):
In the Authentication section, check one or both boxes to set an authentication method:
Only accept mail from the specified IP addresses — The system only accepts mail sent from these IP addresses as coming from your domains.
Require SMTP Authentication — Enforces the use of SMTP authentication to identify the sending domain. Using this option requires your clients to connect via TLS.
The wording here seems a bit misleading and appears to indicate that you can have both of these options enabled without one "interfering" with the other. As I said, I probably should have figured this out on my own - especially since I'm trying to send from a "dummy" e-mail account - but I guess it just didn't occur to me.
I considered deleting this question, but I had done a fair amount of searching before writing this question up and somehow never ran across that particular post. I'm not sure how I could have missed it, but I'm leaving my question here in hopes that someone else has an easier time of finding this solution in the future.

MailMessage only accepts sender with #domain

I wrote a code in .NET to send emails in my application:
Oxygenne + ASP.Net:
mensagem:=MailMessage.Create(configemail[1],toUsers);
mensagem.Subject:=title;
mensagem.Body:=body;
mensagem.IsBodyHtml:=IsBodyHtml;
This works fine when configemail[1] is something like "myemail#gmail.com". However, I have the need to send emails without using domain, something like "myemail".
I am getting this error:
The specified string is not in the form required for an e-mail address
I believe this happens because the code validates if the variable has #anydomain in the string.
Am I able to override it, and let the user try to send emails without usind "#domain" in their address?
So far as I'm aware, SMTP requires all recipient mailboxes to have a domain part. You may be able to interact with a specific mail system via other protocols that allows you to interact with just local mailboxes but you shouldn't expect SMTP tools to be the means of doing so.
Per RFC 5321:
Only resolvable, fully-qualified domain names (FQDNs) are permitted
when domain names are used in SMTP ... There are two exceptions to the
rule requiring FQDNs
The reserved mailbox name "postmaster" may be used in a RCPT
command without domain qualification
Which in turn leads us to the syntax for the RCPT command:
rcpt = "RCPT TO:" ( "<Postmaster#" Domain ">" / "<Postmaster>" /
Forward-path ) [SP Rcpt-parameters] CRLF
So, the only generally applicable form that is available is the Forward-Path, which via a few hops (and ignoring some legacy options not helpful to you here) leads us to the Mailbox syntax:
Mailbox = Local-part "#" ( Domain / address-literal )
So, either way you have to have the # and then your choices boil down to a domain name or an IP address. Note that this may give us an opening though - you may be able to get what you want by specifying the addresses as myemail#127.0.0.1.

Qmail email address without hostname/domain name

In our production a user sent an email to the following address "xxx" (Literally the email is address xxx). This address is within our companies organization (xxx#company.com.ph), I am being asked how it was sent without "#company.com.ph".
I told them it was probably the configuration of our SMTP server as I am sure the application I made is not appending "#company.com.ph" to mails without (hostName/domainName).
Our SMTP server is Qmail in a Unix box. Can anyone tell me what configurations we could check to explain how this happened?
Unfortunately, I do not have a Qmail or Unixbox so I cant test it myself and I don't have access to our production servers so I could really use some help.
PS. Can anyone also give me the correct term for "#company.com.ph" is it the hostName/domainName?
Checks Done
1) According to the administrator - "defaultdomain" is set to "mail.company"
Yes by default qmail will add defaultdomain to any recipient address missing the domain part.
#company.com.ph is the domain name part of the email address.
defaultdomain file by default is in /var/qmail/control directory as from documentation: http://www.lifewithqmail.org/lwq.html#config-files

SMTP server error: Verification failed for 550-No Such User Here 550 Sender verify failed

I'm using
Configure SMTP plugin for wordpress, when I used it in a local server (localhost) it works properly and send me the test email which confirms that it is working. But when I used it in a hosting site (I used Hostgator) it gives me an STMP error.
What is the possible cause of this error? and what is the possible solution?
Thank you.
Based on the second error, and the words "verification failed", and "sender verify" failed, my guess would be that you have not set up SMTP authentication correctly. You are relaying your mail through Hostgator, so they may have specific hostnames / ports that you need to authenticate correctly with to get your mail to flow. I'd suggest syncing with Hostgator on this.

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