(Ruby) Reading Unread POP3 Email

The POP3 protocol does not provide the ability to ask the server which emails are "unread". Furthermore, a pure POP3 server does not even keep this information. Some servers, such as Exchange Server, expose both POP3 and IMAP interfaces. In these cases, information about read/unread status exists on the server, but it is only available via the IMAP protocol. Email clients such as Outlook and Thunderbird keep read/unread information on the client computer. This example demonstrates how UIDLs can be saved to track and read "unread" email.

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# The mailman object is used for receiving (POP3) 
# and sending (SMTP) email.
mailman = Chilkat::CkMailMan.new()

# Set the POP3 server's hostname
mailman.put_MailHost("pop.someMailServer.com")

# Set the POP3 login/password.
mailman.put_PopUsername("***")
mailman.put_PopPassword("***")

# You may keep a list of already-seen UIDLs in a text file:
# If this is the first time you're running this example,
# create an empty text file named "seenUidls.txt"
saSeenUidls = Chilkat::CkStringArray.new()
success = saSeenUidls.LoadFromFile("seenUidls.txt")
if (success != true)
    print "failed to load seenUidls.txt" + "\n";
    exit
end

# Get the complete list of UIDLs on the mail server.
# saUidls is a CkStringArray
saUidls = mailman.GetUidls()
if (mailman.get_LastMethodSuccess() == false)
    print mailman.lastErrorText() + "\n";
    exit
end

# Create a new string array object (it's an object, not an actual array)
# and add the UIDLs from saUidls that aren't already seen.
saUnseenUidls = Chilkat::CkStringArray.new()

i = 0
n = saUidls.get_Count()
while i < n
    if (saSeenUidls.Contains(saUidls.getString(i)) != true)
        success = saUnseenUidls.Append(saUidls.getString(i))
    end

    i = i + 1
end

if (saUnseenUidls.get_Count() == 0)
    print "No unseen emails!" + "\n";

    exit
end

# Download in full the unseen emails:
# bundle is a CkEmailBundle
bundle = mailman.FetchMultiple(saUnseenUidls)
if (mailman.get_LastMethodSuccess() == false)
    print mailman.lastErrorText() + "\n";

    exit
end

i = 0
while i < bundle.get_MessageCount()
    # email is a CkEmail
    email = bundle.GetEmail(i)
    print email.ck_from() + "\n";
    print email.subject() + "\n";
    print "----" + "\n";

    i = i + 1
end

# Save saUidls to "seenUidls.txt"
success = saUidls.SaveToFile("seenUidls.txt")