Authentication

• user <username> - enter the username for the account
• pass <password> - enter the password for the account

Mailbox Status & Information

• stat - see the number of messages in the inbox
• list [msg] - lists all messages or a specific message number along with its size
• uidl [msg] <n> - returns the unique message ID for tracking a specific email
• capa - request a list of the server's capabilities

Mail Retrieval

• retr <msg> – the retrieve command downloads/displays the full content of the specified message number
• top <msg> <n> – retrieves the message header plus a specified number (n) of body lines.

Mail Management & Session Control

• dele <msg> - delete a particular message
• rset - Unmarks any messages that were previously marked for deletion during the session
• noop - performs no operation (can be used as a keep-alive check)
• quit - disconnect from the POP3 server

E.g.:

# telnet 127.0.0.1 110
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
+OK Dovecot ready.
capa
+OK
CAPA
TOP
UIDL
RESP-CODES
PIPELINING
AUTH-RESP-CODE
STLS
USER
SASL PLAIN
.
user nell
+OK
pass thePassword
+OK Logged in.
stat
+OK 278 59431689
retr 278
+OK 691 octets
Return-Path: <jdoe@moonpoint.com>
Received: from moonpoint.com (localhost [127.0.0.1])
	by moonpoint.com (8.14.7/8.14.7) with ESMTP id 6A4122DY022073
	for <nell@moonpoint.com>; Tue, 3 Nov 2026 20:02:02 -0500
Received: (from jdoe@localhost)
	by moonpoint.com (8.14.7/8.14.7/Submit) id 6A4122iG022070
	for nell@moonpoint.com; Tue, 3 Nov 2026 20:02:02 -0500
Date: Tue, 3 Nov 2026 20:02:02 -0500
From: jdoe <jdoe@moonpoint.com>
To: nell@moonpoint.com
Subject: Example email
Message-ID: <20261104010202.GA21379@moonpoint.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.5.21 (2010-09-15)

This is an example email.
.
dele 278
+OK Marked to be deleted.
rset
+OK
noop
+OK
quit
+OK Logging out, messages deleted.
Connection closed by foreign host.
#

Or, if you want to see the size of a particular message, its unique message ID, or just a portion of the message rather than the entire message:

[jdoe@moonpoint ~]$ telnet 127.0.0.1 110
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
+OK Dovecot ready.
user nell
+OK
pass thePassword
+OK Logged in.
stat
+OK 292 60503043
list 292
+OK 292 713
uidl 292
+OK 292 00026d86481e759f
top 292
+OK
Return-Path: <abigail@moonpoint.com>
Received: from moonpoint.com (localhost [127.0.0.1])
	by moonpoint.com (8.14.7/8.14.7) with ESMTP id 6A60FcqT005571
	for <nell@moonpoint.com>; Thu, 5 Nov 2026 19:15:38 -0500
Received: (from abigail@localhost)
	by moonpoint.com (8.14.7/8.14.7/Submit) id 6A60FcLW005570
	for nell@moonpoint.com; Thu, 5 Nov 2026 19:15:38 -0500
Date: Thu, 5 Nov 2026 19:15:38 -0500
From: Abigail Adams <abigail@moonpoint.com>
To: nell@moonpoint.com
Subject: Test email
Message-ID: <20261106001538.GA5472@moonpoint.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.5.21 (2010-09-15)

.
top 292 5
+OK
Return-Path: <abigail@moonpoint.com>
Received: from moonpoint.com (localhost [127.0.0.1])
	by moonpoint.com (8.14.7/8.14.7) with ESMTP id 6A60FcqT005571
	for <nell@moonpoint.com>; Thu, 5 Nov 2026 19:15:38 -0500
Received: (from abigail@localhost)
	by moonpoint.com (8.14.7/8.14.7/Submit) id 6A60FcLW005570
	for nell@moonpoint.com; Thu, 5 Nov 2026 19:15:38 -0500
Date: Thu, 5 Nov 2026 19:15:38 -0500
From: Abigail Adams <abigail@moonpoint.com>
To: nell@moonpoint.com
Subject: Test email
Message-ID: <20261106001538.GA5472@moonpoint.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.5.21 (2010-09-15)

A test message. 

Abigail
.
dele 292
+OK Marked to be deleted.
quit
+OK Logging out, messages deleted.
Connection closed by foreign host.
[jdoe@moonpoint ~]$

[/network/email] permanent link

Proton Mail provides end-to-end encrypted email. If you are transitioning to Proton Mail from another email application and need the contacts you had stored in the other application, Proton Mail provides the capability to import contacts stored in a Virtual Contact File (VCF) or a comma-separated values (CSV) file. VCF, aka vCard, files usually have a .vcf filename extension while .csv is the filename extension for CSV files. To import such files, in the Proton Mail application, click on the Contacts icon on the upper, right side of the Proton Mail window, then click on Import Contacts, then select "Import from .csv or Vcard", then click on the "Choose a file or drag it here" button.

If you want to extract contacts from a Microsoft Outlook Personal Storage Table .pst file, you can use the readpst utility to extract the contacts from the .pst file. A command such as readpst -cv -tc -o contacts_out your-outlook.pst can be used where contacts out is the output directory where you wish the utility to place the contacts (the output directory must exist prior to running the command) and your-outlook.pst is the location and name for the existing .pst file. E.g.:

alice@Wonderload:~/Documents$ readpst -cv -tc -o ~/Documents/contacts ~/Downloads/alice\@example.com.pst 
Opening PST file and indexes...
Processing Folder "Deleted Items"
Processing Folder "Inbox"
Processing Folder "Outbox"
Processing Folder "Sent Items"
Processing Folder "Suggested Contacts"
Processing Folder "Junk E-mail"
Processing Folder "Conversation Action Settings"
Processing Folder "Quick Step Settings"
Processing Folder "Drafts"
Processing Folder "Calendar"
Processing Folder "Contacts"
Processing Folder "Journal"
Processing Folder "Notes"
Processing Folder "Tasks"
	"Suggested Contacts" - 22 items done, 0 items skipped.
Processing Folder "RSS Feeds"
Processing Folder "~ Holly"
Processing Folder "HVIA Members"
	"alice@example.com" - 16 items done, 0 items skipped.
Processing Folder "Tutorials"
Processing Folder "HVIA Renters"
	"Tasks" - 0 items done, 5 items skipped.
	"HVIA Renters" - 1 items done, 0 items skipped.
	"HVIA Members" - 102 items done, 1 items skipped.
	"Tutorials" - 31 items done, 0 items skipped.
	"Contacts" - 127 items done, 4 items skipped.
	"Calendar" - 0 items done, 229 items skipped.
	"Inbox" - 0 items done, 297 items skipped.
	"Sent Items" - 0 items done, 341 items skipped.
	"~ Holly" - 0 items done, 399 items skipped.
alice@Wonderload:~/Documents$

[ More Info ]

[/network/email/protonmail] permanent link

My wife wanted to transition from Microsoft Windows to Linux for privacy and performance reasons, so I installed Ubuntu Linux on her desktop system. She had been using Microsoft Outlook as an email client. I installed Evolution, which is available as a Debian package, as an alternative to Outlook. Evolution has the capability to import an Outlook Personal Storage Table (PST), though that did not work when I tried the process with the PST file Outlook was using under Microsoft Windows. But to try that process, when the Welcome window opens when you start Evolution, click on Cancel to close it. Then take the following steps:

1. Press the Alt+F keys to view the file menu, then select Import.
2. You can click on Next at the Evolution Import Assistant window to proceed with the import of the Outlook Personal Storage Table (PST) file.
3. For the Importer Type, choose "Import a single file" then click on Next.
4. At the Select a File window, navigate to the location of the PST file and select it. The file type in the file type field should automatically change to "Outlook personal folders (.pst)" instead of the default file type of "Berkeley Mailbox (mbox)"

If the option to select Outlook personal folders (.pst) is not in the drop down list of file types, you may need to install the plugin that allows Evolution to import .pst files. To check on the status of the PST plugin on an Ubuntu system, or another Debian distribution of Linux, use the command sudo apt install evolution-plugins evolution-plugin-pstimport.

[ More Info ]

[/network/email/evolution] permanent link

Sendmail is an email server application that is available for many operating systems. It will listen on TCP port 25 for connections from other mail servers that use the Simple Mail Transfer Protocol for email transmissions. As a message submission agent (MSA), another common port it listens on is TCP port 587 for email transmissions from users' email clients. On a Linux system you can use the netstat or ss commands to determine if a system is listening for connections on a particular port. When I checked a Sendmail server to determine whether it was listening on port 587, I could see that it was not listening on that port, though that was needed.

# netstat -an | grep 587
# ss -ln | grep ":587 "
#

When I searched /etc/mail/sendmail.mc for RELAY_MAILER_ARGS, I saw the following lines, which are needed to have Sendmail listen for email transmissions from users on TCP port 587, were already present and were not commented out:

define(`RELAY_MAILER_ARGS', `TCP $h 587')
define(`ESMTP_MAILER_ARGS', `TCP $h 587')

When I searched for DAEMON_OPTIONS, I saw the following:

dnl # The following causes sendmail to additionally listen to port 587 for
dnl # mail from MUAs that authenticate. Roaming users who can't reach their
dnl # preferred sendmail daemon due to port 25 being blocked or redirected find
dnl # this useful.
dnl #
dnl DAEMON_OPTIONS(`Port=submission, Name=MSA, M=Ea')dnl

I removed the dnl from the begining of the line so that I then had the line below, instead:

DAEMON_OPTIONS(`Port=submission, Name=MSA, M=Ea')dnl

I then rebuilt /etc/sendmail/mc and restarted the Sendmail service.

# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
# service sendmail restart
Redirecting to /bin/systemctl restart  sendmail.service
#

I could then see that the system was listening for connections on port 587.

[ More Info ]

[/network/email/sendmail] permanent link

dnl # The following example makes mail from this host and any additional
dnl # specified domains appear to be sent from mydomain.com
dnl #
dnl MASQUERADE_AS(`mydomain.com')dnl
dnl #
dnl # masquerade not just the headers, but the envelope as well
dnl #
dnl FEATURE(masquerade_envelope)dnl
dnl #
dnl # masquerade not just @mydomainalias.com, but @*.mydomainalias.com as well
dnl #
dnl FEATURE(masquerade_entire_domain)dnl
dnl #
dnl MASQUERADE_DOMAIN(localhost)dnl
dnl MASQUERADE_DOMAIN(localhost.localdomain)dnl
dnl MASQUERADE_DOMAIN(mydomainalias.com)dnl
dnl MASQUERADE_DOMAIN(mydomain.lan)dnl
MAILER(smtp)dnl
MAILER(procmail)dnl
dnl MAILER(cyrusv2)dnl
MASQUERADE_DOMAIN(`verizon.net')dnl
MASQUERADE_AS(`moonpoint.com')dnl

After I edited the sendmail.mc file, I rebuilt the sendmail.cf file by restarting sendmail with the command service sendmail restart , which put the following line in sendmail.cf:

C{M}verizon.net

The person who was sending the newsletter died several years ago and I took over maintaining the membership list for the organization as well as distributing the email version of the newsletters to members. Though the account from which the newsletter is sent is intended to be used only for sending the newsletter and members are advised to send an email related to the organization to the organization's Gmail email addresses, occasionally members will reply directly to the "from" address used for the newsletter. When checking the account for that address, I found that someone with a verizon.net address had sent a reply to the account, but if I replied my reply would go not to his verizon.net address, but to his email name followed by my domain name, which would result in the email bouncing since that address would not be a valid address on my server. I corrected the problem by removing the two MASQUERADE lines in sendmail.mc that resulted in the change to the domain name part of email addresses if any email came from a verizon.net address and then restarted sendmail, which resulted in the C{M}verizon.net line being removed from sendmail.cf.

The sendmail.mc file is a human-readable macro configuration file, while the sendmail.cf file is the more complex configuration file actually used by the Sendmail message transfer agent (MTA). The .mc file serves as the source, which is processed by the m4 macro to generate the final, often uncommented sendmail.cf file used by sendmail. The command m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf can be used to rebuild the .cf configuration file after one makes changes to the sendmail.mc file, but the changes won't take effect until sendmail is restarted. Or, on many newer versions of the Linux operating system, one can simply restart sendmail and a new .cf file will be automatically generated and applied to sendmail, if any changes have been made to the .mc file

References:

1. 18.4. The sendmail.cf and sendmail.mc Files
   Linux Network Administrators Guide

Related articles:

1. Modifying the "from" domain of a message with sendmail
   Date: June 1, 2018

[/network/email/sendmail] permanent link

To change the "from" address of a message in the Mutt email client while composing a message, you can use Esc-f, i.e., hit the Esc and f keys simultaneously. You will see a "From:" field appear near the bottom of the window with the current "from" address, which you can edit to replace it with whatever you would like. E.g., in the example below, I am changing the "from" address that the recipients of the message will see from jdoe@example.com to newsletter@example.com (the email address is within the angle brackets with a descriptive identifier before it.

y:Send q:Abort t:To c:CC s:Subj a:Attach file d:Descrip ?:Help               
    From: Joe Doe <jdoe@example.com>
      To: "Bruce K." <bkamen2145@gmail.com>
      Cc: albusd@example.com
     Bcc:
 Subject: Re: July 2025 Newsletter
Reply-To:
     Fcc: ~/sent
Security: None


-- Attachments                                                               
- I 1 /var/tmp/mutt-example-508-23668-418711[text/plain, 8bit, utf-8, 1.4K   




-- Mutt: Compose [Approx. msg size: 1.4K Atts: 1]----------------------------
From: Newsletter <newsletter@example.com>

After I've retyped the "from" address to be the one I want to appear, when I hit Enter, I will see the "from" address replaced with the one I want and can then hit y to send the message to recipients.

y:Send q:Abort t:To c:CC s:Subj a:Attach file d:Descrip ?:Help               
    From: Newsletter <newsletter@example.com>
      To: "Bruce K." <bkamen2145@gmail.com>
      Cc: albusd@example.com
     Bcc:
 Subject: Re: July 2025 Newsletter
Reply-To:
     Fcc: ~/sent
Security: None


-- Attachments                                                               
- I 1 /var/tmp/mutt-example-508-23668-418711[text/plain, 8bit, utf-8, 1.4K   




-- Mutt: Compose [Approx. msg size: 1.4K Atts: 1]----------------------------

For a way to change the "from" address from the command line, see Using a command-line interface (CLI) to send email with mutt.

[/network/email/clients/mutt] permanent link

• Apple
• Google (online)
• Office 365 (onlilne)
• Outlook
• Outlook.com
• Yahoo (online)

Once I had the .ics file, I was able to click on File then Open & Export in Outlook on my wife's PC to open the .ics file I downloaded and add the organization's calendar to her Outlook calendar.

[/network/email/clients/outlook] permanent link

[/network/email/clients/mutt] permanent link

For a mail server running Sendmail email server software, if you wish to block email from a particular "from" address to any email address on the server, you can include the address you wish to block in the /etc/mail/access file. E.g., if you wished to block email from the address spammer@example.com, you can include the following line in that file:

# Block envelope "from" address of spammers
spammer@example.com                     REJECT

Any line beginning with a # is treated as a comment, so the first line above isn't needed, but adding a comment line may help you recognize why the reject statement is in the file. After you have added the line, you need to regenerate the /etc/mail/access.db file, or create a new one if there isn't already one present, using the command shown below (you don't need to restart sendmail):

# makemap hash /etc/mail/access </etc/mail/access
#

This will only work if you have a FEATURE(`access_db')dnl line in /etc/mail/sendmail.mc. E.g., a line like the one below:

FEATURE(`access_db', `hash -T<TMPF> -o /etc/mail/access.db')dnl

If you don't have such a line, you will need to add it. If the line begins with dnl, you will need to remove the dnl at the beginning of the line, since that "comments out" the line.

[ More Info ]

[/network/email/sendmail] permanent link

SSLCertificateFile /etc/letsencrypt/live/support.moonpoint.com-0001/cert.pem
SSLCertificateKeyFile /etc/letsencrypt/live/support.moonpoint.com-0001/privkey.pem
Include /etc/letsencrypt/options-ssl-apache.conf
SSLCertificateChainFile /etc/letsencrypt/live/support.moonpoint.com-0001/chain.pem

When I checked the expiration of that security certificate, I saw it was valid until May 17.

# openssl x509 -enddate -noout -in /etc/letsencrypt/live/support.moonpoint.com-0001/cert.pem
notAfter=May 17 04:02:51 2024 GMT
#

You can determine the location of the .pem file used by Dovecot by looking for the ssl_cert variable in /etc/dovecot/conf.d/10-ssl.conf.

[ More Info ]

[/network/email/dovecot] permanent link