-2
votes
0answers
14 views

operating own smtp server vs using some ESP [duplicate]

my question may seem old but i have to ask this because I did not find anything helpful for my scenario. for my business, i need to send huge number of email daily, more than 200K. i have gone ...
20
votes
4answers
2k views

What are the best methods for catching snowshoe spam?

I'm using Smartermail for my small mailserver. We've been having a problem lately of getting waves of snowshoe spam that follow the same pattern. They come in batches of 3 or 4 at a time. The ...
33
votes
2answers
9k views

What are SPF records, and how do I configure them?

This is a canonical question about setting up SPF records. I have an office with many computers that share a single external ip (I'm unsure if the address is static or dynamic). Each computer ...
-1
votes
2answers
262 views

How can I reject spam before reaching SMTP on Postfix

My server has started receiving thousands of attempts to use my mail server to send spam from dynamic.hinet.net. The attempts are always rejected, but it's non-stop. I'd like to block these attempts ...
14
votes
3answers
3k views

Prevent mail being marked as spam

This is a canonical question about avoiding outgoing mail being classified as spam. Also related: Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User? What ...
2
votes
1answer
190 views

Why are messages queued and not sent with sendmail?

I am having trouble with one of my sendmail servers. Users are informing me about that registration emails do not arrive. The logfile claims that the message has been queued, but the queue is empty: ...
0
votes
0answers
23 views

Emails ending up in gmail spam folder [duplicate]

Emails from my dedicated server are ending up in spam folder in gmail even though the server is not blacklisted and with good reputation - see below. the server level issues that would cause this ...
1
vote
2answers
58 views

How to find out who is sending email

I have a server which doesn't have much activity. Today, suddenly server load went higher than 12 which compared to its normal value(0.5) is way too high. I checked and found out that postfix is being ...
0
votes
2answers
123 views

How reliable is validating email domain by reverse DNS MX record checking [duplicate]

This question is not about how to protect against spam or validate a particular email user. But how reliable is validating emails domain (does it exists at all) by reverse dns. What are the pitfalls ...
0
votes
2answers
49 views

How do IPs end up on the spam blacklists

I don't know if this is the right place to ask this kind of question but here goes. I have 3 IPs on my server, which I'm running for shared hosting. The main shared IP gets blacklisted sometimes, ...
0
votes
0answers
24 views

postfix filter “Do you want to have more lovers?” [duplicate]

My postfix is currently set up to check email content and reject by keywords. However, I can't think of a good way to block this kind of emails: Return-Path: <gievcyopa@beamtele.com> Delivered-...
0
votes
1answer
35 views

How to prevent spammers sending bogus@mydomain emails out of my name [duplicate]

Lately I receive a lot of Delivery Status Notification (Failure) e-mails. Bogus spam email is sent from blablaxx@mydomain to other emailadresses, and bounce back to my catch-all info@mydomain with ...
8
votes
2answers
9k views

In postfix, how to enforce tls + auth over 587 while leaving tls optional for 25

I would like to host mail services for some domains. I have succesfully setup postfix to consult sql for those virtual domains. What I would like to do is: For connections on 25: Deny relaying (...
-1
votes
1answer
53 views

How to improve spam protection using postfix? [duplicate]

I try to improve the spam protection of my postfix install for several weeks now, but I still receive spam. What I've done so far: Added SpamAssassin Added SPF record Tuned rejection rules Now I'...
0
votes
4answers
4k views

smtpd_helo_restrictions = …, reject_unknown_helo_hostname occasionally rejects mail I care about, how to handle?

I have configured my postfix as follows: smtpd_helo_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unknown_helo_hostname This is working well because most spambots don't seem ...

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