Simple Mail Transfer Protocol. A protocol for delivering e-mail from an end user to a server for storage and later retrieval by the intended recipient.

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is there a risk in increasing esmtp header line length against rfc5822 - asa/pix question

Have a question towards the 998 bytes limitation on the esmtp header line length. We have noticed the asa is dropping emails coming from various external mail servers with the header line length ...
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1answer
54 views

Receiving strange data over SMTP where body is one line of random characters

I have a website that has an smtp server open on port 25. There is no outbound functionality on the smtp server. We just parse attachments from our users, then 'queue' the email in a dummy queue. So ...
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3answers
1k views

Why enable SMTP STARTTLS if OpenSSL is dangerous?

There are a bunch of people in the anti-surveillance movement who are virtually demanding that I enable SMTP STARTTLS support in my environment, in order to enable opportunistic MTA-to-MTA encryption. ...
3
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1answer
134 views

What type of attacks will a SMTP server face if it does not have ratelimiting while sending mails?

Assume a web site with some kind of mailer option, that doesn't implement any rate limiting: This enables users to send an unlimited amount of email per second. Will SMTP face possible DoS attacks ...
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2answers
49 views

What is the proper terminology for the various SMTP tunnel encryption solutions?

I'm writing up documentation and want to ensure that I'm using proper terminology. 1) What is the proper technical term for the SMTP tunnel encryption standard that typically starts on TCP/25, ...
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2answers
2k views

Test STARTTLS configuration of SMTP server

Is there an easy way to test an SMTP server to check for configuration issues associated with STARTTLS encryption, and report on whether it has been configured properly so that email will be encrypted ...
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2answers
123 views

What are the security risks for a business that has an insecure email system [closed]

For instance if the email system uses POP3 legacy protocol and SMTP but is not encrypted, yet the business continues to use it for daily purposes both internally and externally, what could be the ...
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2answers
122 views

Why does a business need to secure its email system? [closed]

Why is important for a business to secure its email system?
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2answers
834 views

What threats come from CRLF in email generation?

I have an application where a code scanner has identified CRLF injection possibilities in some classes related to email generation. I understand how CRLF injection could be used against me on ...
2
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3answers
335 views

Is STARTTLS a security-vulnerability?

After reading about STARTTLS and SSL and performing a scan/pentest at our server I have the next question regarding security: Is this STARTTLS warning below a security-vulnerability? And if so why? ...
159
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3answers
23k views

Don't understand how my mum's Gmail account was hacked

My mum (on Gmail, using Chrome) received an email from a friend's Hotmail address. She opened the email (very obviously a phishing email) and clicked a link in it. This opened a webpage with loads of ...
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3answers
4k views

How (in)secure is POP/IMAP/SMTP

I'm making a few assumptions about basic email security, and I want to confirm or clarify some of these points to make sure I understand the big picture. Please correct me where I'm mistaken: The ...
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1answer
830 views

Email Spoofing by SMTP Message-ID?

Many of my users today got email from docs#@mydomain.com (where docs# was between docs0 and docs8 or so, and mydomain.com is obviously changed from my real domain name), with the sender name of ...
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1answer
1k views

What are the realistic chances of email being intercepted via SMTP/TCP-IP? [closed]

Dear SMTP and TCP/IP network security gurus: I'm curious about what is the realistic risk of sensitive information (such as a email pdf attachment) being intercepted/read by a hostile party from a ...
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2answers
333 views

how to find out if a program sends data to internet (without permission)?

We have an application to save our customers data (some kind of CRM). This application has been written in Delphi and is a client/server application. This program apparently is sending out ...
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2answers
455 views

Why don’t SMTP servers just require all senders to be authenticated before accepting mail?

Why don’t SMTP servers just require all senders to be authenticated before accepting mail?
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3answers
2k views

What is the hack attempt going on when I see: did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA

When I look at my sendmail logs, by far the most common "error" I see is the following: Nov 22 16:49:50 MyHostname sendmail[18832]: rAMMnj2u018832: [IP address redacted to hide the guilty] did not ...
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1answer
732 views

SMTP injection, how it is done and what can it cause?

There are a few things that I dont understand about the injection. The injection is something along this line > . MAIL FROM: mail1@gmail.com RCPT TO: mail@gmail.com DATA EMAIL data . Here are ...
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3answers
3k views

What does the email header-line “message opened by mailclient” mean?

Today a Belgian MP claimed (backed up by a security expert) that her email headers show that her email was read during routing (text in Dutch). The published screenshot of the headers highlights the ...
2
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1answer
185 views

Should admin make SMTP to do sanity checks?

Open SMTP relays are bad. The major email providers such as Gmail and Yahoo do some sanity checks such as the following at the SMTP level to prevent spam to arrive the users' mailboxes: $ telnet ...
2
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1answer
179 views

Using X-actual-recipient to divert email

Has anyone noticed exploits involving the use of "X-Actual-Recipient" to covertly divert e-mail from an intended recipient to someone else? I have been told that only someone with root access on the ...
3
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2answers
615 views

Can unencrypted email be read or altered while it is in transit?

If email is not secure while in transit, exactly how can it be read by unintended parties? Can an attacker read SMTP traffic while it is between the sender and recipient?
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4answers
393 views

A Secure Email Host Architecture

How would one go about creating a secure email architecture? I'm thinking specifically about protecting email from routine surveillance from oppressive regimes and corporations. I had a think about ...
3
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1answer
196 views

Checklist for securing smtp

What are some things, one should know when setting up an SMTP server, which supports ESMTP protocol. I have disabled relaying, and only enabled TLS authenticated transfers. when I telnet to my server, ...
4
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1answer
1k views

How secure is Integrated Windows Authentication for IIS SMTP?

I have a Windows SMTP server that is currently allowing the "AUTH LOGIN" method of authenticating. As I now know, this is simply a base-64 encoding of the username and password, which is basically as ...
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2answers
461 views

Keyloggers and Email Accounts [duplicate]

This morning, I was experimenting with some keyloggers and noticed that they have a feature to send e-mails to the attacker. How can these e-mails be intercepted? Let us say that I have a packet ...
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1answer
929 views

What are the ports used by Online Email Accounts such as Yahoo Mail, Gmail, etc.?

Let us say that I send an email using Yahoo Mail or GMail. Can this email be intercepted using a packet sniffer? On which port does the email travel? HTTP, SMTP, POP3?
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2answers
88 views

What information should I provide to a website or organization when notifying them that their domain may be sending out spam?

Over the past few days, I've received several spam emails coming from the addresses of a school district. I don't know much about email message headers, but since they contain numerous references like ...
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2answers
2k views

What justification is there for Comcast to block SMTP port 25 outbound from residential service?

Within the last week, Comcast seems to have started blocking port 25 outbound from their residential internet service. I can sort of understand why they might justify blocking it inbound as perhaps ...
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3answers
678 views

SMTP and SSL/TLS

If I understand correctly, communication between SMTP servers may be encrypted but is not required. Because it is optional, does it really have benefits? When server A connects to server B, both of ...
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1answer
1k views

How to study the packets sent by a keylogger

One of my friends runescape account got hacked through key-logger. He downloaded a runescape gold generator from a file sharing site and tried to use it. I have a strong doubt that it is a key-logger. ...
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1answer
1k views

Windows System event log warnings for smtpsvc

I get a lot of the following type messages: Message delivery to the remote domain 'particular domain or IP address' failed for the following reason: The remote server did not respond to a connection ...
4
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3answers
695 views

How do you verify a certificate belongs to a domain?

I'm using PHP and trying to verify a SSL certificate belongs to the SMTP domain/IP I'm connecting to. Currently I can verify the certificate is valid using the following code $resource = fsockopen( ...
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2answers
79 views

SPF and Articles from News Sites

Suppose I activate SPF in my environment. I am now strictly enforcing SPF records from sending domains. There are many execs in the company who like to forward news stories from CNN and such to ...
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1answer
986 views

Why is Message Labs sending mail in plaintext?

I have several SMTP servers on various networks around the world, and all of them are getting mail through ESTMPS - extended SMTP using TLS. So the email coming from GMail, MSN, Yahoo, as well MOST ...
2
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2answers
706 views

Using tor with SET to bypass firewall policy?

I'm doing a credential harvesting attack using SET from backtrack. I want to sent a spoof email using an open relay server. However, any outbound connection for smtp is blocked by the firewall. I ...
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2answers
2k views

Send credit card info by email from HTTPS and SMTP on SSL

A client asked me to receive credit card info of his costumers by email. I know that is a very very not secure way ... But if the page with the input form is on HTTPS, and then i use a smtp (like ...
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2answers
542 views

Issues with using a mail server that doesn't support authentication to send mail?

I have noticed the mail server we use at work (provided by our web-host) doesn't require any authentication to send mail through. I understand you easily spoof sender address' in emails, but I'm ...
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2answers
549 views

Is it possible to fake the mail server address?

Suppose that I send an E-mail to someone. Is it possible to fake mail server address - for example, while I used my own local mail server, I send it as if it was sent from Microsoft mail server. (I ...
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2answers
428 views

End of mail spoofing?

I've made the simpliest e-mail program in C#. using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using ...
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2answers
1k views

How is mail automatically sent from my account?

Today I have received an email with an 'out of office' notification, as a reply to one of my emails, which I actually didn't send. I think it was sent automatically from my address, as a result of ...
0
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1answer
282 views

block changing IP addresses on port 25 SMTP

A script is currently being run against my exchange server attempting to access resources on port 25 SMTP. This is generating event 4776 within Windows event logs. How can I stop this? Would I need to ...
2
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2answers
273 views

Is it unsafe to allow apps other than Outlook to send email via the Exchange server?

My application is a .NET Windows Forms client, one of whose functions is to allow the user to send personalised mailshot emails to opted-in recipients stored in the database. The emails are sent ...
5
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2answers
1k views

If I send an email over SSL, will it always be transmitted over SSL?

This is largely a question of how MTAs and different components communicate. I'm curious that if I send an email using SMTP over SSL to my MTA, can it's next jump to the next MTA or MDA be insecure? ...
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1answer
1k views

How can I find the process that is trying to use smtp to send email?

Previously I asked Who (which process) is calling curl? and I got very good answers (this answer in particular) which basically replaces the curl binary with a shell script that logs each call to curl ...
12
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3answers
769 views

Can I expect my e-mail to be routed securely?

If I connect to my e-mail server via SSL (SMTP/SSL) and the recipient also only checks his e-mail via SSL (web/https or IMAP/SSL), does this - generally speaking - increase the security for the ...
7
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1answer
2k views

Email SSL security?

I use IMAP and I only access my email through SSL. However, the settings for encrypted email access seem a bit more complicated that https. Can someone explain the security implications of the ...
24
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4answers
14k views

What steps do Gmail, Yahoo! Mail, and Hotmail take to prevent eavesdropping on email?

I would like to ask what happens when an email is sent from gmail, yahoo or hotmail public web email services? I don't understand email protocols in details, but as far as I know email traffic is ...
8
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1answer
161 views

Long running SMTP session

I recently noticed an SMTP session on my server which started when a remote host connected but never seemed to result in any emails being delivered. I could see that it was probably a SPAM site and so ...