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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42
votes
5answers
6k views

Why is end-to-end encryption still not default in mails?

I am not a cryptographer. Maybe that is why I don't see the issues with integrating PGP into SMTP. In my head: Lea requests the server of Luke's domain jedi.com to tell her the public key of luke@...
3
votes
3answers
537 views

How to know an SMTP server is securely configured [closed]

I have set up an SMTP server for personal use, and I used Postfix for that. However, Postfix has a lot of different options for how to configure it, and I'm guessing by configuring it incorrectly you ...
-1
votes
1answer
65 views

How do Bots Spam Where Outgoing SMTP is blocked

I have read,that bots in an internal network talk directly to External Mail servers instead of going through the Internal Mailserver to deliver spam. Query If it's true, than how do Bots spam do so ...
1
vote
1answer
96 views

How can I contract an email tracking service and be silent about it?

I use a customized e-mail and my web-master, who is also the domain owner, doesn't allow me to see the settings that the DNS provides. Some DNS services provide, beside domain name registration, ...
0
votes
0answers
29 views

Detecting Spamming activities of Botnets

Remarks Hello Everyone,thanks for being a nice platform for expressing Everyone's Doubts/Views. Problem Statement I want to detect spamming activity of botnets Background Information about ...
3
votes
1answer
183 views

Does the use of JavaScript make ProtonMail insecure?

I like the look of ProtonMail. However, what has stopped me from signing up is that JavaScript seems to be used at various points in the site, and for someone to read your email they must click on a ...
4
votes
2answers
148 views

Is it secure to send sensitive data through gmail smtp with nodemailer?

I have an application that would send sensitive data through email to specific users. I have setup a google business account which provides email addresses on my business domain. I will be sending ...
0
votes
1answer
77 views

Mail : non existent domain FROM field

I'm wondering if during the process of sending a message, the domain indicated in "from" field is checked? I know there is no integrity control of the from field, but I tried to send a message to an ...
2
votes
4answers
155 views

Is it possible to fake incoming IP?

I would like to whitelist an IP address on my smtp server so that non-authenticated emails on connections originating from that IP could be routed. I control that other IP, so I can make sure that ...
0
votes
2answers
51 views

Secure way for bulk mailbox verification to avoid IP Blacklisting

We have built an API that verifies a address existence in the respective MX using RCTP command. Their are many services available out there but we like to do it again since we have few clients who ...
3
votes
2answers
118 views

Why do email that didn't pass SPF checks go to my mailbox?

I tried a website that supposedly sends spoofed email. I sent myself an email impersonating another email address and the message showed up in my yahoo mailbox even though according to the headers it ...
-3
votes
1answer
46 views

How does SMTP facilitate sending spam? [closed]

My friend tells me that there are exist weakness of the Simple Mail Transfer Protocol (SMTP) that make make it easy to send spam. Is this true?
0
votes
1answer
298 views

Why doesn't outlook 2013 meet modern security standards?

It is required to turn on the allow less secure apps setting in order to be able to use a gmail account with outlook 2013, despite it is using the IMAP and SMTP services with SSL protocol enabled. ...
0
votes
1answer
84 views

OpenSSL gmail - receiving Please log in via your web browser and then try again

Using openssl as below when I do EHLO auth login and then enter my username and password I get the following error: Please log in via your web browser and then try again. Learn ...
0
votes
1answer
170 views

Mail server security: Mails to internal receivers with faked sender address

I noticed that I am able to send emails from my company's mail server to internal receivers from faked inhouse sender addresses without problem and I'm wondering if this should be supposed a security ...
0
votes
1answer
50 views

smtp-auth attack ?

it looks someone or something is trying to hack our Exchange. Exchange Server Transport Protocol Logs: it appears the internet facing IP on the firewall has not been locked down correctly, so is ...
4
votes
2answers
81 views

Should I email contents of a https form submission

I am building an online registration form for a voluntary organisation in the UK and am considering data security measures. The form will be served up over https and there may be an optional payment ...
0
votes
0answers
55 views

script for analysis of tcpdump log file

I'm trying to get the following metrics from my tcpdump log file: (1) one-way delay, (2) request/response delay, (3) packet loss, (4) overall transaction duration and (5) delay variation (jitter). ...
4
votes
3answers
4k views

I'm getting spam e-mail…from myself?

I noticed yesterday that I had received spam e-mail, but my own e-mail address was listed as the sender. Naturally, I changed my password. This is probably a spoof, but I don't know enough about ...
6
votes
2answers
2k views

Can (and should) TLS be strict about the ciphers it supports?

When trying to establish a TLS channel to outlook.com in order to relay SMTP traffic I get connection failures and have to continue without encryption. An example of such a connection: openssl ...
0
votes
3answers
205 views

Is VRFY command enabled on SMTP server usually considered a vulnerability? [closed]

Messing around I found a critical SMTP server with VRFY command enabled.
2
votes
2answers
129 views

TLS capable SMTP store-and-forward server — does it have to store private keys?

I know that email is inherently insecure anyway, but considering that pretty much everyone that I send email to is using a large, somewhat-trusted cloud provider, (hint, starts with G) I would expect ...
6
votes
1answer
2k views

How to reject e-mails spoofing your own domain targeting your employees at Office365?

One problem Office365 users deal with is that an external SMTP server can spoof the domain of an organization and send e-mails to the domain users; where the e-mails appear to be from employees of the ...
6
votes
2answers
2k views

How to prevent abuse of SMTP by sending spam emails?

I'm not an admin, I just created a website, and there's also a mail server on the server I payed for from my hosting provider. Most for what I learnt about mail servers is from an internet tutorials. ...
1
vote
0answers
72 views

How to inform other sysadmins their email encryption is broken [closed]

Does anyone have a good template email to use to send to remote system/mail/security administrators to alert them to the fact that emails to them would not be getting through either at all or securely ...
-2
votes
1answer
94 views

Recommendations for SMTP DoS [closed]

I have an opened SMTP server that allows me to send emails. The problem is that I can send a massive amount of emails (80,000+) to a specific mailbox and block all the other legitimate emails (that ...
0
votes
2answers
68 views

Is there a way to attack STARTTLS + certificate pinning probed from multiple places?

I just had this discussion on IRC and I have to admit I did not understand why other users were not convinced this would be enough... Let's say I would like to protect e-mails sent out from my ...
2
votes
2answers
507 views

Rationale behind hiding originating IP address in emails?

Gmail has been hiding originating IP addresses for quite some time now. Hotmail and Yahoo have started doing this too. Apart from obvious privacy implications of revealing the sender's IP address, is ...
2
votes
4answers
389 views

How can I stop an IP from trying to use my mail server?

I have recently set up my first email server, and I look at the logs in /var/logs/mail.log to see what is happening, I notice this one IP does this multiple times every day for the last so many weeks :...
-1
votes
3answers
331 views

SMTP injection: where am I wrong?

On another thread a user was trying to use SMTP injections and, as a test, trying to inject a supplementary recipient for this email. My understanding of the issue preventing him from succeeding were ...
3
votes
1answer
625 views

Phishing email from Avast - Headers look totally legit?

Below is the email with headers. I never registered on the site, so it's clearly phishing, but the links in the email point to the real Avast site. The delivery path also looks legit since both IP ...
6
votes
2answers
8k views

Perfectly secure Postfix MTA (SMTP) configuration

I want to secure my root server (further) service by service, starting with the SMTP service (Postfix MTA) as the most busy one. I the course of setting everything up, I read a lot about security and ...
3
votes
4answers
292 views

How webmail's authorisation should work?

I'm building a webmail client (like gmail). It allows the user to browse emails and send them. Under the hood, php uses IMAP and SMTP to talk with email server. user->webserver->mailserver When user ...
1
vote
1answer
209 views

Email account password change via email-to-script

I host a mail server (postfix and dovecot) and I wish to set up a password change feature (especially useful when creating a new address provided with a temporary password). Does my scenario has ...
0
votes
1answer
840 views

Is my Postfix and Dovecot configuration secure?

Today I set up my first server with Dovecot and Postfix. These are excerpts from the configuration files: Dovecot: disable_plaintext_auth = yes ssl = required ssl_prefer_server_ciphers = yes ...
3
votes
1answer
281 views

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 ...
0
votes
1answer
120 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 ...
11
votes
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. ...
2
votes
1answer
2k 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 ...
1
vote
2answers
88 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, ...
17
votes
2answers
30k 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 ...
-1
votes
2answers
526 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 ...
-9
votes
2answers
214 views

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

Why is important for a business to secure its email system?
13
votes
2answers
1k 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 URL-...
5
votes
3answers
1k 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? ...
174
votes
3answers
30k 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 ...
16
votes
4answers
20k 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 ...
1
vote
1answer
3k 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 "...
1
vote
1answer
4k 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 ...
2
votes
2answers
724 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 ...