Questions tagged [postfix]

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64
votes
1answer
11k views

Unusual mail headers show evidence of MTA attack. Have I been pwned?

Today I found an extremely unusual email in my catchall inbox, without subject, sender or content. My Gmail client for android reported the mail was sent by me, triggering a nuclear alert in my mind. ...
1
vote
1answer
60 views

Postfix SMTP - Can I use SSH public keys instead of sasl password

I am relatively new to managing mail server, although i am familiar with webhosting servers not running dedicated email services. Postfix is configured to use sasl-password authentication I have ...
2
votes
1answer
166 views

Why are my emails going to spam?

I have been trying to learn about phishing emails. I have read up quite a bit on it. I setup a domain somthing.tk (free domain), hosted a website on a VPS (Digital Ocean). Set up my own mail transfer ...
0
votes
0answers
53 views

spam that penetrated reject_sender_login_mismatch in postfix

We have the following in postfix's main.cf: smtpd_recipient_restrictions= permit_sasl_authenticated, permit_mynetworks ... smtpd_sender_restrictions = permit_mynetworks, reject_sender_login_mismatch ....
0
votes
1answer
151 views

Is `tls_preempt_cipherlist = yes` in postfix a good idea nowadays?

Postfix' own documentation says it may cause issues, but only mentions "Windows 2003 Microsoft Exchange clients". Everything else I've found (first was CheckTLS, as far as I've been able to find, that'...
1
vote
1answer
1k views

Is TLS 1.3 supported in Dovecot 2.3.4 and Postfix 3.3.2?

I would like to configure an email CentOS 7-based server to use TLS 1.3. Currently it uses TLS 1.2 for securing the SMTP and POP3 sessions. For SMTP I use Postfix software and for POP3 I use Dovecot ...
0
votes
1answer
39 views

Linking mail server with application database

I have a web application running on node.js, backed by a MongoDB database which stores user data etc... I'd like to offer my users an email account, so I've set up a mail server using Postfix, dovecot,...
2
votes
1answer
2k views

How should output of fail2ban postfix-sasl look like

I want to be sure that fail2ban is properly banning failed postfix SASL login attempts. When I do iptables -L I can see list of banned hosts for SSHD, but I can't figure out a way to see banned ...
-1
votes
1answer
326 views

What is the most secure communication between firewall, and DMZ

I have 2 virtual machines. (Vmware esxi 6) They are both opensuse 42.3 (tumbleweed) Firewall (iptables,ipset,dhcpd,dns only) mail/web server. (apache,dovecot,postfix) The web server can not ...