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Internet Mail Consortium Report: UBE-RELAY IMCR-006, February 1, 1998
Summary
Many people working to combat unsolicited bulk email (UBE) believe that restricting the ability of UBE senders to use unrelated SMTP gateways would help reduce the amount of UBE. Companies that have had UBE sent through their SMTP servers have experienced losses in terms of time and money due to the responses they receive.
It’s important to note that relaying messages through an SMTP server is standard practice for users affiliated with that server. However, malicious UBE senders often exploit SMTP relays that they have no connection with, passing the cost of transmission onto others.
It is generally in the best interest of SMTP server administrators to restrict relaying to known users. Many commercial and freeware SMTP servers allow this control, and it is becoming an increasingly essential feature for those purchasing or using SMTP services.
Until now, only anecdotal reports have surfaced regarding the percentage of publicly-known SMTP servers that allow unauthorized relaying. The percentages reported vary widely, and test methodologies were often unspecified. To address this, IMC recently conducted a large-scale test to determine how many SMTP servers allow unauthorized relaying.
Results showed that over 55% of SMTP servers allowed relaying from users not affiliated with the server. This figure is higher than many previous estimates, demonstrating that more work is needed to reduce the number of open relays to the point where UBE senders struggle to find available servers they are not authorized to use.
Collecting Test Data
IMC’s 38 mailing lists consist of 6,427 names, representing deliverable addresses hosted at 2,839 unique mail servers (i.e., unique domains appearing to the right of the “@” symbol in email addresses). For each of these 2,839 mail servers, the lowest-numbered MX (Mail Exchanger) record was identified, followed by the corresponding A record. If no MX record existed, the A record alone was used. In cases where neither an MX nor A record could be found, the mail host was discarded. This left 2,813 valid hosts and their corresponding IP addresses.
A random sample of 500 of these 2,813 hosts was selected for the relay test.
Performing the Test
The test was conducted on the evening of January 24, 1998. Each SMTP command’s response was logged, and the program also recorded how far it progressed in sending a relayed test message. The domain “ABCDE.COM” was used as an existing domain associated with IMC, though it does not correspond to the actual “abcde.com” domain.
The steps of the test were as follows:
Connection to Port 25: The test program attempted to connect to the IP address associated with each host on port 25. If the connection failed, the program terminated and logged “CONNECT.” A total of 28 servers failed to connect.
SMTP Greeting (EHLO/HELO Command): After connecting, the program issued an EHLO command using “mail.ABCDE.COM” as the domain of the test machine. If EHLO was rejected, the program tried a HELO command. If both commands were rejected, the program logged “EHLO” and terminated. None of the tested servers rejected the SMTP greeting.
MAIL FROM Command: The program issued the command “MAIL FROM:phoffman@ABCDE.COM.” If this command was rejected, the program logged “MAIL” and terminated. All tested servers accepted this command.
RCPT TO Command: The next step was to issue the “RCPT TO:ron@ABCDE.COM” command. Most SMTP servers that block relaying are expected to return an error at this point since the message is not intended for local delivery. A total of 182 servers responded with a 4xx or 5xx error code, indicating that they blocked the relay attempt.
DATA Command: If the RCPT TO command was accepted, the program issued a “DATA” command and sent the following message:
To: ron@ABCDE.COM
From: phoffman@ABCDE.COM
Subject: Relay test
Sent from
[name of the host sent to]
[timestamp]
If the DATA command was rejected, the program logged “DATA” and terminated. Two servers that had accepted the RCPT TO command returned 4xx or 5xx responses to the DATA command. One rejected the message because it wasn’t local, while the other rejected it due to the absence of a date field in the message.
QUIT Command: The program issued the “QUIT” command and logged “OK.” All 288 remaining hosts responded with a 2xx success code.
Analyzing the Results
The responses recorded in the test logs are as follows:
Response
Number
Percent
CONNECT
28
5.6%
TO
182
36.4%
DATA
2
0.4%
OK
288
57.6%
Several reasons could explain the 5.6% failure rate to connect. One likely factor is that some hosts on the mailing lists were no longer operational, as some lists had not received messages in several months. Additionally, if higher-numbered MX records had been tried for the hosts that failed to connect, the failure rate could have been lower.
Of the 288 hosts that fully accepted the message, 259 successfully delivered it to the recipient. Twenty-four hosts returned messages to the “From” address, indicating that the message could not be delivered. Additionally, one human postmaster followed up with a manual message stating that relaying would not be tolerated.
Experts in the SMTP protocol generally agree that the proper time to reject a message due to relaying violations is after the RCPT TO command. Indeed, most servers that blocked relaying did so at this stage.
IMC plans to run the test again in the future to track whether more organizations begin to restrict unauthorized relaying. The results from future tests will be incorporated into this report.
This article is based on “Allowing Relaying in SMTP: A Survey” by Paul Hoffman, published by the Internet Mail Consortium (IMCR-006, February 1, 1998).
Link to Web Archive: https://web.archive.org/web/19991106005353/https://www.imc.org/imcr-006.html
Tutorial: How to Buy an ICO (Initial Coin Offering)
Initial Coin Offerings (ICOs) are a popular method for new cryptocurrency projects to raise funds. This tutorial will guide you through the steps of buying an ICO safely and effectively.
Step 1: Research the ICO
Before investing, thoroughly research the ICO to understand the project, its goals, the team behind it, and its potential for success. Key points to consider:
Whitepaper: Read the project’s whitepaper to understand its purpose, technology, and roadmap.
Team: Research the team members’ backgrounds and track records.
Community and Media Presence: Check for active community engagement on platforms like Reddit, Telegram, and Twitter. Look for mentions in reputable media outlets.
Step 2: Prepare a Digital Wallet
To participate in an ICO, you need a digital wallet that supports the ICO’s token. Most ICOs are based on the Ethereum blockchain, so a wallet like MetaMask, MyEtherWallet, or Ledger is commonly used.
Install and Set Up a Wallet: Download and install your chosen wallet. Follow the setup instructions, ensuring you back up your wallet’s recovery phrase securely.
Obtain Your Wallet Address: Your wallet will provide a unique address for receiving tokens.
Step 3: Acquire the Required Cryptocurrency
ICOs typically accept payments in popular cryptocurrencies like Bitcoin (BTC) or Ethereum (ETH). Purchase the required cryptocurrency from a reputable exchange, such as Coinbase, Binance, or Kraken.
Create an Account: Sign up for an account on the exchange.
Verify Your Identity: Complete the necessary KYC (Know Your Customer) verification process.
Deposit Funds: Deposit fiat currency or other cryptocurrencies into your exchange account.
Buy the Required Cryptocurrency: Purchase the amount of BTC or ETH needed for the ICO.
Step 4: Participate in the ICO
Once you have the necessary funds in your wallet, follow these steps to participate in the ICO:
Visit the Official ICO Website: Ensure you are on the official website to avoid phishing scams.
Register for the ICO: Complete any registration process required by the ICO. This may include KYC verification.
Send Cryptocurrency to the ICO Address: The ICO website will provide an address to send your BTC or ETH. Double-check the address before sending any funds.
Wait for Confirmation: After sending your funds, wait for the transaction to be confirmed on the blockchain. This may take some time, depending on network congestion.
Step 5: Receive and Store Your Tokens
Once the ICO is complete, you will receive the project’s tokens in your wallet.
Add the Token to Your Wallet: Some wallets require you to manually add the token by entering its contract address, symbol, and decimals. This information is usually provided on the ICO’s website or in their communications.
Store Your Tokens Securely: Ensure your tokens are stored securely in your wallet. Consider using a hardware wallet for added security.
Step 6: Monitor and Manage Your Investment
After participating in an ICO, monitor the project’s progress and manage your investment accordingly.
Follow Project Updates: Stay informed about the project’s developments by following their social media channels, newsletters, and community forums.
Track Token Performance: Use cryptocurrency tracking tools or platforms to monitor the performance of your tokens.
Consider Long-Term Storage: If you believe in the project’s long-term potential, consider holding onto your tokens for an extended period.
Tips for a Successful ICO Investment
Do Your Own Research (DYOR): Never invest based solely on hype or recommendations. Conduct thorough research and due diligence.
Beware of Scams: Be cautious of fraudulent ICOs. Verify the legitimacy of the project and its team.
Invest What You Can Afford to Lose: Cryptocurrencies and ICOs are highly speculative and volatile. Only invest money you can afford to lose.
By following these steps and tips, you can navigate the process of buying an ICO with greater confidence and security.
Some providers might leak your actual physical address, when sending an email, by displaying your IP address to the recipient.
Some have privacy concerns, with what they want to reveal to providers about their whereabouts… well whatever your personal reasons may be, we have some good news.
After working on this we’re happy to announce, Kingmailer is no longer displaying the IP address, also known as “no SMTP IP leak”.
Kingmailer will now show localhost 127.0.0.1 as your physical location.
This is how you can verify if this is truly true and if we are truly offering this (which we are):
Kingmailer gives you the option to create custom email addresses /email alias, such as yourname@example.com, so that you can:
Build more customer trust and confidence
Increase recognition of your company name
Complement and extend your business website
Get your business found more easily online
You can create multiple custom addresses and have emails delivered to your Gmail inbox or other email provider. You can send and receive emails using your custom email address.
This is what you get:
Option to create multiple custom email addresses (for multiple users)
Add more than 1 domain
Option to add your custom email in Gmail, Proton or other email provider
Emails per month. For Routing emails only. Have questions? Email us info@kingmailer.co. We accept Bitcoin, PayPal and all major cards. Thank you for supporting small business.
Want to find out how? Follow the steps below.
Here’s how to get started. If you need help, just send us an email info@kingmailer.co:
Create Endpoints
An Endpoint is where you want the emails to be delivered, it can be your Gmail-address. In your Kingmailer-account go to Routing (1), click on Address Endpoints (2) and then on Add your first address endpoint (3).
Enter your email address
Enter your email address (1) and click Create address endpoint (2).
Create a Route
The Endpoint is there, so now you can create any email address you like, all emails send to this address will be delivered (forwarded/routed) to the Endpoint aka your Gmail address.
Enter a username (1) for your email address for example info@domain so there you’ll enter just info. Select the domain (2) (which you already verified in your account: SPF, DKIM, MX and Return Path). Choose the Endpoint (3) which you created earlier.
Sending Emails from Gmail
Go to Settings > Accounts and Import > Add another email address > Send mail as
Add your email address
Enter your name and your email address, allow Treat as an alias and then Next Step
Enter the SMTP credentials
You can use these settings:
SMTP Server: kingmailer.org Username: enter your SMTP username Password: enter your SMTP password Port: 587, 465, 25 or 2525 Secure connection: TLS
We wrote a small list with the best Mailjet alternatives with price for you to explore. These are SMTP providers active today in the Transactional Email services space.
Company
Price /mo
Emails /mo
Amazon SES
$1
10,000 (Usage based)
Mandrill
$25
25,000
Kingmailer
$11.95
20,000
Postmark
$10
10,000
Pepipost
$25
150,000
Sendgrid
$14.95
40,000
Seen an error? Or have a suggestion? Leave a comment.
For this list we have used Slant and Capterra.
We wanted to present our users with a list of best Mailjet alternatives.