sending an email to GitHub no-reply email ID - github

I was looking for the email address of a few profiles on GitHub and came across the no-reply email IDs. I know that these email IDs are created to make our personal email private, but I was wondering what happens if we mail to that no-reply address, I tried to mail me with my friend's email account and didn't receive any error neither did I receive the mail in my inbox. So what happened to that mail?

If you try to send mail to that domain, it will be returned as undeliverable.
In order to send mail to a domain, that domain must have either one or more MX records that provide the names of hosts to which mail can be delivered, or one or more A or AAAA records pointing to hosts which have a mail server running. In this case, users.noreply.github.com has no MX records, and it is a CNAME for github.github.io, which points to hosts which do not run a mail server.
When you attempt to send a mail to a server and it can't be delivered immediately, it is usually queued by your mail server, and if it remains undeliverable after some time (by default five days), it will bounce. Normally, you will receive a bounce message from your mail server indicating that the mail wasn't able to be delivered.
The point of those addresses is to allow users to attribute their commits to the correct account without having to receive emails. It wouldn't be very useful to prevent people from sending spam (or, in some cases, hostile or abusive emails) if the addresses weren't totally undeliverable.

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Sendgrid - Activity says email delivered but email not received

I tried to send an email through sendgrid. I have a custom domain myself#contoso.com. If i try to send an email to user1#gmail.com with the from address as myself#contoso.com,then,the email is delivered to gmail with "via". When i try sending email to myself#contoso.com with the from address being myself#contoso.com the activity says the email is delivered however, in outlook client i have not received the email. What is it that I can try or do?
I have tried whitelisting contoso.com but it did not work
This is not an answer, as it doesn't help work out why the emails that are "Delivered" have not been received, but this is SendGrid's note on why Email messages with the “Delivered” status are not received:
Twilio SendGrid posts the Delivered event after the destination server accepts the message with a 250 OK response. Once an email is accepted by the destination server, we are unable to see what happens to the message. The receiving server could send it to the inbox, queue it for later delivery, put it into the spam folder, etc.
Often times, a recipient domain will initially accept a message for delivery, and then apply additional filtering afterwards. In this situation, we would have posted the Delivered event, but not have any insight into the additional filtering. Any additional Twilio SendGrid events for your email message would be triggered by recipient engagement (i.e. open/click events, unsubscribes, etc.).
Also note that at the time of writing, that answer had 26 downvotes (and zero upvotes) on the SendGrid website, probably indicating that many other users have experienced this problem.
I had several issue solving this problem. The most important part is to set "Sender Authentication" from sendgrid to your domain dns. There is a instruction here. I'm using godaddy, so the link to set dns is https://dcc.godaddy.com/manage//dns .

550 Verification failed: No such user. Sending mail with Mailgun to CPanel email

I am creating a webservice with Mailgun to send out emails. It will BCC my own domain's email for every email sent out. Assuming my domain is "example.com". For every email sent out to a customer, say, customer1#gmail.com, I will BCC its content to sales#example.com.
Currently, the domain example.com and its email is hosted on a server with CPanel.
In Mailgun, I have added and verified the domain example.com. Using this domain, I've sent a mail to customer1#gmail.com and sales#example.com. The email is sent without issues to Gmail, however when sending to sales#example.com, I keep getting the error Server response: 550 550 Verification failed for <bounce+e0f051.e0179a-sales=example.com#example.com> No Such User Here.
What's baffling here is that if i send the email via Mailgun with another verified domain such as anotherexample.com, and then using this, I send my mail to sales#example.com. The email arrives perfectly fine without errors.
So far, the things I've tried:
Added Mailgun suggested SPF and DKIM
Modified SPF to include my CPanel server's IP (together with Mailgun SPF)
Deleted both the SPF and DKIM (one at a time and both at once)
Verified that the email sales#example.com exists. Using the CPanel webmail's interface, I can send and receive emails just fine.
Tried updating the CPanel MX entries Email routing from Local -> Automatic -> Remote. ("Local" works the best. If its set to "Remote", email sending and receiving doesnt work at all, even if mails are sent through Gmail/Hotmail).
My current MX settings are:
Priority 0: mail.example.com
My current Zone file records on CPanel:
example.com A <some ip>
mail.example.com A <same ip as above>
The code I am using to send mails via Mailgun (Ruby):
mg_client = Mailgun::Client.new 'xxxxxxxxxxx'
message_params = {:from => from_email,
:to => customer.email,
:bcc => bcc_email,
:subject => MessageTemplate.email_subject,
:text => message}
result = mg_client.send_message('example.com', message_params).to_h!
I currently do not have the SPF and DKIM records in the zone files. I've added and removed them and they had no effect on the error (still delivers fine to Gmail too).
I've spend the whole on this, scouring forums and whatnot but can't seem to find a solution.
If at all relevant, I have a 301 redirect of example.com to www.example.com(Which has a CNAME pointing to another server). But I've researched and found out that 301 redirect does not affect emails.
I don't think this is a send-side problem. You're sending to sales#example.com, but you're getting errors relating to bounce+e0f051.e0179a-sales=example.com#example.com, which is a typical VERP address. Now, VERP addresses are fine, so long as you're expecting them. Given that you are not apparently providing that explicit address to MailGun, I assume that they are generating that address automatically. I would check their documentation for how they generate return-path (envelope sender) addresses, and either override the sender address (with just sales#example.com), or configure handling of those VERP addresses on your own inbound mail server.
Here is a mailgun explanation
This error occurs due to what is termed Sender Address Verification (SAV). During SAV, an email server performs an MX lookup upon the domain (example.com) listed within the message envelope's Mail-From field. SAV typically rejects the message if,
the sender's (in this case, Mailgun's) MX records are not configured for that domain AND
the domain of the message envelope's Mail-From field does not match the domain of the message header's From field.
https://help.mailgun.com/hc/en-us/articles/360011804533-Sender-Verification-Error

Spam mails Joe-Job via Amazon AWS

since a few days our internal email info#ourdomain.com seems to go bananas and sends out emails to all sort of email addresses. Some of those emails bounce and we receive Mail Delivery Failed emails every minute.
Here is our setup:
Domain hosted at Germany's 1und1 provider
Nameserver configured on Amazon Route 53
MX server mx01.kundenserver.de and mx00.kundenserver.de
Rails application hosted on heroku
I called the support at 1und1 and they told me to set a SPF record which I did:
"v=spf1 a mx ~all"
after researching the topic via http://www.spf-record.de/
Unfortunately this did not resolve the problem.
Honestly I am cluesless now what to do to prevent this random email sending.
Our account could have been hacked but the password was already changed.
Any of your email account or script/code compromise can cause outgoing spam emails. If outgoing emails are originating from particular email account and you find large outgoing email account from particular email account, you should consider to reset the password of that email account immediately. Also, compromised email sending script/code can can cause outgoing spam.
If "from" email address on spam email is none of your existing account then "From" email address is getting authenticated from any of your existing email account for which you should inspect SMTP logs of mail server(you should have administrative access of mail server)
Mail server IP address should not be blacklisted,please check IP here :- http://mxtoolbox.com/blacklists.aspx
If IP address is blacklisted, you can request IP whitelist after you identify and fix the outgoing spam source as RBL keeps IP address blacklisted until they find the spamming activity relaxed.
SPF and PTR record should be correct so that email recipient server can trust the sender mail server.
Bounce back email and spam email header can help to identify the issue more preciously.
This happened to me before, I had a "refer a friend" feature on my website and someone use an automated script to send emails to a ton of people. My server wasn't comprised, it was just bad coding in the feature that I installed that allowed my mail server to send mail to different people on my behalf.
Since the email is coming from you, your SPF/DKIM will check out just fine.
So thing about all the points on your website that can send email and see if any of them can be compromised.
Also you'll want to do a blacklist scan, I use this service it does more then 200+ blacklist: https://www.unlocktheinbox.com/blacklist/bl/
Make sure you scan both your domain name and IP address. But before you take any action to remove yourself, you should wait 24 hours until after you fix the exploit on your system. Requesting removal and popping up again can get you permanently listed.

How to redirect all bad emails to the one master email using DNS

Sometimes when people try to send me messages they misspell email address and I lose the message.
Example:
If my email is ivijan.stefan#something.com and my client misspell and write evan.steven#something.com or iivijan.stefan#something.com etc, I will lost my email.
Is there a way to use MX record or some DNS setup to server notify me and send message on one master email address where I can see that someone try to contact me and see message?
DNS servers do not understand what an email is. It may be possible to do this at your mail server end though. Look for documentation for catch-all email addresses to receive all email that would have been sent to non-existent email addresses. Note that this may expose you to huge amounts of spam from bots that target well known email addresses like admin#domain or postmaster#domain.

To where goes bounce mails, From or Reply-to

We are having a system that sends mail on behalf of the user (the user provide his own mail address).
The mails are send via our server and are set up to with our company mail address as From (as many of our clients have disallowed third party to send mails withe their address as From) and with the users mail address in the Reply-to.
Is it true that bounce mails are going to the Reply-to address rather than to the "From" address.
No, bounces will go to the reverse-path address in the SMTP envelope, which is usually (if you did not specify otherwise) the same as the From address supplied in the mail headers. Because you (correctly) use your company address as a reverse-path, bounces will be sent to your company. See Sender Rewriting Scheme for an example how it is possible to send bounces to the original user.