dusko + mailserver   484

What characters are allowed in an email address?
See RFC 5322: Internet Message Format (http://tools.ietf.org/html/rfc5322) and, to a lesser extent, RFC 5321: Simple Mail Transfer Protocol (http://tools.ietf.org/html/rfc5321).

RFC 822 also covers email addresses, but it deals mostly with its structure (http://tools.ietf.org/html/rfc822#section-6.1).

In addition to ASCII characters, as of 2012 (https://tools.ietf.org/html/rfc6531) you can use international characters above U+007F (http://www.utf8-chartable.de/unicode-utf8-table.pl), encoded as UTF-8 (https://en.wikipedia.org/wiki/UTF-8#Description).

For validation, see Using a regular expression to validate an email address (https://stackoverflow.com/questions/201323/using-a-regular-expression-to-validate-an-email-address).
mailserver  email 
4 days ago by dusko
sendmail ("Bat Book") - Online
By Bryan Costales & Eric Allman; ISBN 1-56592-222-0, 1050 pages.
Second Edition, January 1997.
sendmail  mailserver 
4 weeks ago by dusko
mail-tester.com -- newsletters spam test
Check your newsletter's spam score and quality. This tool's free, and pretty.
mail  sysadmin  mailserver  smtp  email 
6 weeks ago by dusko
Send a multipart/alternative email with sendmail
Contains a clear example of a multipart/alternative email message.
sendmail  mailserver  unix  cli 
7 weeks ago by dusko
FreeBSD as a Secure Mail Server Using sendmail and imap-uw
Building a simple sendmail server that supports auth-based relaying as well as SSL/TLS encryption while using FreeBSD is fairly straightforward. FreeBSD's base sendmail is very flexible and lends itself well to this type of setup.

The goal is to have working sendmail, ipop3d and imapd (using imap-uw) that play nice with Microsoft e-mail clients, don't require any extra password maintenance, uses FreeBSD's included sendmail and uses applications from FreeBSD's ports system.
sendmail  mailserver  freebsd  smtp 
8 weeks ago by dusko
Mail Server on FreeBSD with OpenSMTPd, jails, amavisd-new, DKIM, SpamAssassin, DSPAM
OpenSMTPd, jails and amavisd-new for virus scanning and DKIM signing and spam classification using SpamAssassin and DSPAM.

Required ports

WIP mail/spamd Throttling
mail/opensmtpd OpenSMTPd MTA
mail/opensmtpd-extras OpenSMTPd extra filters
security/amavisd-new "A Mail and Virus Scanner"
mail/spamassassin Apache SpamAssassin e-mail classifier
mail/dspam Bayesian e-mail classifier
security/clamav Open source virus scanner
DSPAM SpamAssassin plug-in
One of MariaDB/MySQL, PostreSQL, SQLite or Hash database

mail (opensmtpd, dovecot)
scan (amavis, spamassassin, dspam, clamav)
mailserver  freebsd  smtp  dkim  spf  dovecot  opensmtpd 
8 weeks ago by dusko
How do I see how sendmail will deliver a message?
You can see the mailer, host, user triple sendmail will deliver a message to a recipient by using the "/parse" command in address test mode:

sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> /parse user@some.dom
Cracked address = $g
Parsing envelope recipient address
canonify input: user @ some . dom
. (output deleted)
final returns: user @ some . dom
mailer relay, host smtprelay.foo.com, user user@some.dom
The "mailer" is the delivery agent that will do the actual delivery. You can find it in your sendmail.cf file by looking for the line starting with"Mmailername", in this case "Mrelay". The relay mailer is an ESMTP mailer that allows 8 Bit data with out any correct MIME labeling.

The "host" is the host that sendmail will connect to, in this case an SMTP relay "smtprelay.foo.com".

The "user" is the actual recipient address that will be passed to the next host for delivery, in this case "user@some.dom"
sendmail  mailserver 
8 weeks ago by dusko
logwatch -- what's a -bs?
> what's a -bs?

A sendmail commandline parameter used by programs like pine to send mail. If the sender is not a trusted user this warning is written to the logs.
smtp  log  mailserver  server  sysadmin  sendmail 
8 weeks ago by dusko
Mbox to Maildir conversion (forked from version on dovecot.org)

Updated to add a '-v' option that will strip a directory extension (much like '-r' would strip an mbox extension.
email  mailserver  sysadmin  perl 
8 weeks ago by dusko
Courier worksheet
For scalability, we are going to arrange for exim to deliver all local mail in Maildir format. This creates a subdirectory called "Maildir" in the user's home directory, which in turn contains three subdirectories: new, cur and tmp. Messages are written into tmp, moved to new when delivery is complete, and moved to cur when read. Each message has a long unique filename based on the hostname and the time of day.

Because each message is stored in a separate file, it is much faster for the pop3 daemon to start up every time a user connects. It also allows for safe delivery onto a shared (NFS) disk backend.

Exim does not include any software for retrieving mail from a mailbox, so we need to install additional software. Courier is a mail system which includes a number of packages. In fact it has its own MTA, but we will ignore this (it is still under heavy development, and does not have the flexibility needed for an ISP environment). The components we are interested in are the IMAP/POP3 servers and 'sqwebmail', the webmail server.

You can get the entire courier system as one package (including the MTA), or just the components. We will get the authlib, pop3/imap and webmail components separately.

Remember: in the command examples given below, commands shown with the prompt "$" should be run as your normal non-root userid. Only those commands with prompt "#" need to be run as root.
mailserver  imap  mta 
9 weeks ago by dusko
Zimbra Recent Account Activity (beta)
A Zimbra extension that allows the user to monitor their recent login and account activity. This is important to keep the user's account safe.

Designed for Zimbra version 8.7.

Bugs and feedback: https://github.com/Zimbra-Community/account-history/issues


Use the automated installer:

wget --no-cache https://github.com/Zimbra-Community/account-history/raw/master/account-history-installer.sh -O /tmp/account-history-installer.sh
chmod +rx /tmp/account-history-installer.sh
mailserver  zimbra 
october 2017 by dusko
DMARC Weekly Digests by Postmark
A free tool to monitor & implement DMARC.

DMARC is a standard that prevents spammers from using your domain to send email without your permission - also known as spoofing. Learn why DMARC is important ( https://postmarkapp.com/support/article/892-what-is-dmarc ).

We will process reports from major ISPs about your domain's DMARC alignment and turn them into beautiful, human-readable weekly email digests, absolutely free.
mailserver  email  smtp  spam 
october 2017 by dusko
Blocks and Reputation Lists - Email - Mail Server
Blocks and Reputation Lists
Useful DNS Toolboxes
ISP Postmaster/Delisting/Whitelisting Pages
Best Common Practices for Senders
MXToolbox Email Header Analyzer
smtp  mailserver  spam 
september 2017 by dusko
SNDS - Smart Network Data Services - Outlook.com - Hotmail
SNDS gives senders access to detailed data about individual IPs, and it also includes our Junk Email Reporting Program, which lets you receive reports when users junk your messages. Now you can view IP data and manage feedback loop settings from one convenient website.
smtp  mailserver  spam 
september 2017 by dusko
How to Check Blacklist - Check Blacklists Email
Good Corporate / Enterprise SPAM Firewalls and Blacklists list.
september 2017 by dusko
Open Relay Online Tester - Open Relay Check
Check domains' mail servers for Open Relay configuration.
mailserver  smtp  email  spam 
august 2017 by dusko
Blacklist Lookup - Senderscore
About the Return Path Reputation Network Blacklist
mailserver  spam 
august 2017 by dusko
Blacklist Check by WebSitePulse
The Blacklist check queries the major DNS Blacklists - Sorbs, Spamhaus,NJABL, DSBL, CBL and PSBL for specific IP address or hostname and returns whether it is blacklisted for sending spam, as an open proxy relay or for other possibly malicious activities.
mailserver  spam 
august 2017 by dusko
Five Ways to Check Your Sending Reputation
Five Ways to Check Your Sending Reputation via @SendGrid
august 2017 by dusko
Email attachments
Keep in mind that the size of your file on disk or in memory may not be the same as the size of the file once it is attached, as files must be encoded as text to be sent. You can expect an increase in size of up to 30%.
email  mailserver 
august 2017 by dusko
Cisco Talos - Reputation Lookup -- Previously SenderBase
The Talos Email and Web Traffic Reputation Center (formerly known as SenderBase).
mailserver  cbl  spam 
august 2017 by dusko
Sendmail: Clear / Delete / Flush Mail Queue -- With qtool.pl tool/script
Explains how to delete or flush Sendmail queue using UNIX / Linux / BSD command line option or qtool.pl script.
sendmail  mailserver 
august 2017 by dusko
Remove messages from sendmail queue matching subject
In the sendmail contrib/ directory there's a perl script qtool.pl that lets you safely make interventions on spool directories while sendmail is running. You can delete, bounce, move, and filter by age, size, sender, recipient and subject (amongst other things).

Inexplicably, it is not included with the main CentOS sendmail package, you can find it in the sendmail-doc rpm though (thanks to kubanczyk for noting this), or you can extract it from the source distribution ( ftp://ftp.sendmail.org/pub/sendmail/sendmail-current.tar.gz ). It has minimal dependencies, they should all be part of a normal perl installation.

To delete messages use -d:

qtool.pl -d -e '($msg{headers}->{Subject} =~ /whatever you need/i)' /var/spool/mqueue
To move them to an offline mqueue directory (safer):

mkdir /var/spool/mqueue-junk
qtool.pl -e '($msg{headers}->{Subject} =~ /whatever you need/i)' \
/var/spool/mqueue-junk /var/spool/mqueue
Note it's "qtool.pl destination/ source/". Locked files (those with a "*" by the queue ID in mailq output) will not be moved, you may need to retry to catch those.

You have the option of running that queue later with sendmail -qR [...] -O QueueDirectory=/var/spool/mqueue-junk .

(Older versions of qtool.pl are known to not parse the headers correctly, you need to omit the first letter on most headers, e.g. $msg{headers}->{ubject} instead of {Subject}
sendmail  mailserver 
august 2017 by dusko
How do I permanently delete e-mail messages in the sendmail queue and keep them from coming back?
You will often find the suggestion to remove files from Sendmail's mqueue directory with for instance rm /var/spool/mqueue/* or worse (rm -rf etc.). IMHO, this is plain dangerous. It will work in many cases but I recommend to fasten your seat belts. Simply removing all files from mqueue might delete legitimate messages.

To stop Sendmail before removing queued messages is good advice especially if many messages need to be removed. However, if only a few messages are to be removed or if the queue is cleaned up on a regular basis e.g. by means of a cron job there is actually no need to stop Sendmail. In the worst case one of the messages will be re-queued which will almost certainly be removed when you try again.

On the contrary, stopping Sendmail (e.g. in Ubuntu with service sendmail stop) might not be sufficient. Even when stopped some (child) processes might still be running. One would have to wait until they finished (recommended) or kill them.

In order to safely remove messages from mqueue you need the messages' queue IDs. The IDs are shown in the log after "sm-mta[...]:". The IDs from your log excerpt are o530SlbK009365, o4VHn3cw003597, ... For each of the IDs 2 files are stored in mqueue, one starting with "qf", the other starting with "df".

mailq is generally used to list the queue's content. It shows the IDs in the first column. Furthermore, you should consult mailq's output because it also shows whether a message is active/currently being processed.
sendmail  mailserver 
august 2017 by dusko
Deleting mail from the mail queue
Sendmail does not provide a command-line argument to remove messages from the mail queue. It may be necessary to manually remove messages from the mail queue rather than allowing Sendmail to attempt redelivery of messages for Timeout.queureturn days (5, by default).
The proper way to remove messages from the mail queue is to use the qtool.pl program included in the contrib subdirectory of the Sendmail source code distribution. qtool.pl uses the same file locking mechanism as Sendmail.
The preferred method of queue removal is to use qtool.pl. ---- In order to remove mail from the queue, you have to delete the df* and qf* files from your mail queue directory, generally /var/spool/mqueue. The qf* file is the header of the message and the control file, and the df* file is the body of the message.
sendmail  mailserver 
august 2017 by dusko
Need help configuring Sendmail relay/Connection refused errors
You can look at individual messages in your queue: Go to the queue directory and you will have two files for every email, one starting with df* and the other with qf*. Combined they compose the entire message (one contains information in regards to the queue details, the other the email content... yes purposely simplified explanation :-) ). If you look at the details and decide you want to remove the message from the queue, you can just delete both files for the same queue ID. Alternatively, you could move all the files to another directory which would remove them from the queue, where you could then look through at your leisure and move back any you actually want to try and resend (I have never run into a queue ID problem doing so.. but naturally you are stepping in the middle of a the normal sendmail process by doing this).
mailserver  sendmail 
august 2017 by dusko
Postmaster info - AOL
Information on methods and support for issues concerning mail
mailserver  sysadmin 
august 2017 by dusko
Anonymous remailer
An anonymous remailer is a server that receives messages with embedded instructions on where to send them next, and that forwards them without revealing where they originally came from. There are Cypherpunk anonymous remailers, Mixmaster anonymous remailers, and nym servers, among others, which differ in how they work, in the policies they adopt, and in the type of attack on anonymity of e-mail they can (or are intended to) resist. Remailing as discussed in this article applies to e-mails intended for particular recipients, not the general public. Anonymity in the latter case is more easily addressed by using any of several methods of anonymous publication.
august 2017 by dusko
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