Hot answers tagged email
25
Checking the headers I see that SPF and DKIM pass correctly. I have no problem with GMAIL, YAHOO, and other, but hotmail seems very strict.
This is correct. Hotmail / outlook.com are insanely strict for .. really no sensible reason at all. You have checked the obvious things:
SPF
DKIM
reverse DNS
My IP is not listed in any backlist, I used: ...
12
This is a fairly common source of confusion. There are two places in a standard email transmission where the to: address is specified - once in the "envelope" and once in the visible email headers.
The envelope recipient address is specified during the SMTP transaction, and you will never see the value that is set there. It is solely used by the SMTP server ...
12
I've managed over 100 separate mail environments over the years and have used numerous processes to reduce or help eliminate spam.
Technology has evolved over time, so this answer will walk through some of the things I've tried in the past and detail the current state of affairs.
A few thoughts about protection...
You want to protect port 25 of your ...
11
If there is no MX record, SMTP servers will fall back to the A record.
If there was no A record, the mail would probably bounce immediately, with a DNS misconfiguration error.
If you had an A record set up, pointing presumably to your web host, then any mail servers would have attempted to send your mail to the web host.
If the web host has an SMTP ...
10
What you're proposing is to effectively re-implement your monitoring system (by feeding the current system's alerts into another monitoring system that's smart enough to know something is wrong if it's not constantly reassured that everything is fine).
This almost certainly is not what you need. What you need is a combination of on-site and off-site ...
10
That is not a MX record, it's a SPF record. Usually you would use a TXT record to store SPF information since most DNS servers haven't implemented the SPF RR Type yet.
Your existing SPF record should probably just be updated to reflect the requirements in the invoicing system:
v=spf1 a mx ptr include:mydomain.co.uk include:_spf.bidsketch.com ~all
If the ...
9
Your message is being rejected as spam because it precisely matches the profile of a very common malware distribution scheme: messages claiming to be order or shipping confirmations, with PDF attachments.
My suggestions:
Clean up the grammar. "This is purchase order document for purchase order #1001"? Broken English sounds incredibly spammy, and although ...
9
Since you clarified that you want an email for each successful authentication, pam_notify is a great candidate module for this.
Add it as a session required line at the end of your /etc/pam.d/sshd or equivalent file.
9
Partly, I endorse what others have said; partly, I don't.
Spamassassin
This works very well for me, but you need to spend some time training the Bayesian filter with both ham and spam.
Greylisting
ewwhite may feel its day has come and gone, but I can't agree. One of my clients asked how effective my various filters were, so here are approximate stats ...
8
I am using a number of techniques which reduce spam to acceptable levels.
Delay accepting connections from incorrectly configured servers. A majority of the Spam I receive is from Spambots running on malware infected system. Almost all of these do not pass rDNS validation. Delaying for 30 seconds or so before each response causes most Spambots to give ...
8
Point a secondary MX record your temporary server. Here's a quick example:
gmail.com. 1299 IN MX 5 gmail-smtp-in.l.google.com.
gmail.com. 1299 IN MX 10 alt1.gmail-smtp-in.l.google.com.
When it comes time for maintenance, drop your primary server offline. Since anything sending mail to it should be non-interactive, nobody will really ...
8
So this means I guess that before sending the mail google made a query if the target mail
server will accept it
No. It means when google tried to deliver it, the server responded with user unknown.
More in details:
550 550 5.1.1
ANyhow...
READ THE DOCUMENTATION (smtp protocol) there actually IS a command to ask whether a mailbox exist.
Here ...
8
Situations like these are the result of a couple of factors:
No formalized education on mail usage
Folk-wisdom based transmission of common tasks like vacation rules and how to set up automatic filers
Lack of pain for not deleting anything
These days, we're not quite at the point where a majority of the overall workforce has been dealing with email their ...
7
Ignore them. It's not your job to manage mail on behalf of other companies. If the mail was sent to your system, whether by mistake or not, the mail is yours, not theirs. Sooner or later someone might notice that they're not receiving their messages and then they might look into it, hopefully ending with them telling the sender to use the correct address. In ...
7
First, that SPF line is completely useless. The +all on the end means anyone can send e-mail on behalf of your domain, and it should be considered authentic. Further, that SPF record looks wrong in all sorts of ways, though I can't be sure without knowing more about your environment.
Some servers will even hold this against you. On the servers I run, if ...
7
I don't see anything wrong with your headers, or anything obvious that you're doing wrong, but I would like to point out that, yes, hotmail (as well as live and msn and outlook webmail) are very strict, and tend to classify a lot of mass-mailings as spam, even when they shouldn't be.
A Google search on hotmail emails marked as spam turns up scores of ...
7
You want to prevent this sort of thing in the future? Use a real MTA instead of Google Apps. As you've discovered, it is certainly possible to relay emails through a GApps account, but it's far from ideal, and frankly, it's not what that service was built to do. They give you zero visibility into logs of any sort, which you'd need in order to troubleshoot ...
7
Mailchimp have an excellent article on How To Avoid Spam Filters
Update: Ok, seeing as I got slammed for just giving this link (to be fair its contents probably wouldn't solve your problem here), I've added more specific to what you're sending.
I suspect its the text you're using. 'Please confirm your email address by clicking the link' - I think you ...
7
I am sorry I might be late to the party here. If you are still looking for a solution, I spent a weekend figuring out how to provide Auto Configuration (autodiscover what Outlook 2010 calls it) for most popular email clients including iOS.
I wrote it all down in a blog post here: http://moens.ch/njpvg.
Outlook 2010 actually does a combination of DNS lookup ...
7
Somewhere in your NAGIOS config, you should have a definition of the command used to send email notifications. If it's anything like mine, this will say
define command{
command_name notify-service-by-email
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: ...
6
My first quick check would be whether you're from Saudi Arabia, as the "received-from" IP is from a pool of home DSL users in SA. If not, my first instinct would be that no, it's not from you.
Second you can check your system logs on the mail server, and see if it's showing any outgoing mail.
Third, check that your router is only allowing outgoing activity ...
6
google [or anyone else] will validate spf agains the ip address they see connecting to them. in that case it'll be ip address of your postfix server; you cannot fix it - it's by design....
by design spf has an 'issue' with forwarding unless message is 'repackaged' and sender address rewritten to the one of forwarder.
6
Nevertheless, if there is something I can or should do about this -
I'd like to know
Unfortunately, there isn't. You are at the mercy of the providers receiving the email to know it's 'complete' spam and discard it without issuing a bounce (which is not very likely).
If you haven't already setup SPF records, you should consider doing so. This will ...
6
Congratulations, you've just received your first backscatter spam.
Unfortunately, the root cause of backscatter spam is badly configured mail servers which accept a message before determining that it's undeliverable and then attempt to return it to the "From:" address, which is obviously fake.
If there aren't a lot of them, you can forward them to ...
6
A common configuration is that email destined to addresses "inside" the organization does not require authentication, while "outbound" email does require authentication. This allows an organization to receive inbound email while not becoming a source of spam sent by unscrupulous random people on the internet.
This is often implemented by having completely ...
6
The best practice is don't unless you REALLY have to (the security of this machine is THAT critical).
If you REALLY have to, you don't want to muck about with shell .rc files that people can change - that's a half-baked solution.
The Right Way is probably to use the audit facilities built into Linux (see the man pages for auditd, and its configuration file ...
6
The problem you're having is that "mail server" is an imprecise term. Some people take it to mean "MTA" (because that's all you need to have a server that handles mail), whilst others take it to mean a server that receives mail and stores it for users to manipulate, while still other people have other definitions entirely.
The four software packages you ...
6
Answer: it depends. Most secondary server setups just hold the mail until the primary comes back up, at which point the mail is either delivered or bounced.
If you have either a separate user database that both servers have access to (eg LDAP) or you regularly clone your account list between the servers, then you could probably configure a mailserver to ...
6
If the mail server you are telnetting into is the authoritative server for the domain you specified in the RCPT TO: address (example.com in the example above), it is likely nothing to be concerned about. That simply means that your mail server is accepting mail for addresses in the domain you have set it up for. As @joeqwerty points out, this is how SMTP ...
6
You could also consider disabling the catch-all address and simply reject mail to unknown users, so the sender gets immediately notified via NDR that he mistyped something.
As a side effect this can reduce the load on the mailserver massively since you don't have to process spams to randomly generated adresses in your domain.
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