When Do I Send Emails?

Work and the holidays have been distracting me from blogging and fun side projects for a couple of months, so I'm easing back into it with a really quick and easy Gmail data-wrangling post.

When I first started playing around with my Gmail data, I mentioned that I wanted to get some of the stats that Xobni used to provide before they were swallowed by the Yahoo! black hole. A couple of the simpler stats to compile are "what days of the week do I send most of my email?" and "what time of day do I send the most emails?".

In order to do any time-based analysis on my emails, I'm going to need the dates and times they were sent. So I've taken the PowerShell script from a while back and made a slight modification; in the $props hash I'm adding a field called SentDate:

$props = @{
    Id = $mimeMessage.MessageId
    To = $mimeMessage.To.ToString()
    From = $mimeMessage.From.ToString()
    FromEmail = $fromEmail
    Subject = $mimeMessage.Subject
    Body = $bodyText
    Format = $actualFormat
    SentDate = $mimeMessage.Date.ToUniversalTime()

MimeKit provides the sent date of the email as a DateTimeOffset; to keep things consistent, I'm converting everything to UTC at this stage.

From there, I import the data into pandas as per usual and filter it down to just the emails sent by me:

import pandas as pd
import numpy as np
import humanfriendly
import matplotlib.pyplot as plt

df = pd.read_csv('../times.csv', header = 0)

fromMe = df.query('FromEmail == "[my email]"')

It turns out that indexing your data by date/time in pandas is pretty easy; you just create a DateTimeIndex:

temp = pd.DatetimeIndex(fromMe['SentDate'], tz = 'UTC').tz_convert('America/Denver')

Here I'm telling pandas to create an index by the SentDate field, and that the field is already in UTC. Then I'm converting all of those dates and times to my local timezone so that the data makes sense from my local perspective. This mostly works, because I mostly live in the Mountain timezone. Some of my data will be a little skewed because of emails sent while traveling and a few months where I lived in the Eastern time zone, but not so much that I care. In a later post I might look at how this data changes over time, which is more interesting (I might even be able to identify when and where I was traveling based on that data).

But for now, let's break down the data in temp and shove it back into the original dataset:

fromMe['DayOfWeek'] = temp.dayofweek
fromMe['Hour'] = temp.hour
fromMe['Year'] = temp.year

Now for each email from me, I've got a column that tells me what hour of the day and day of the week it was sent. From there, aggregating it and charting it are a snap:

# Number of emails sent by day of week
sentDayOfWeek = fromMe.groupby(['DayOfWeek']).agg({'Id' : 'count'})
sentDayOfWeek['Id'].plot(kind='bar', figsize=(6, 6), title='Emails Sent By Day Of Week')

# Number of emails sent by hour of day
sentHourOfDay = fromMe.groupby(['Hour']).agg({'Id' : 'count'})
sentHourOfDay['Id'].plot(kind='bar', figsize=(6, 6), title='Emails Sent By Hour Of Day')

The data is about what I'd expect; more emails on Monday than any other day (0 == Monday on this chart) and the majority of emails sent during the workday (with a dip around lunch).

Aggregating by year provides a bit of mystery, though:

sentYear = fromMe.groupby(['Year']).agg({'Id' : 'count'})
sentYear['Id'].plot(kind='bar', figsize=(6, 6), title='Emails Sent By Year')
The numbers vary quite a bit more than I'd expect. 2004 makes sense; I only started using Gmail in July of that year. And the next couple of years shows me using Gmail more and more over my old Lycos account. The spike in 2011 also seems reasonable, as that's when I stopped working at an office with an Exchange server, so my day-to-day email load shifted. But the dips in 2012 and 2015? No idea. I'll have to dig further into those.

Simple Photo De-duplication with PowerShell

After several failed attempts and false starts over the course of the last decade or so, this summer I vowed to finally get my wife's photo library and my own properly merged. For various reasons, we both had large libraries of photos from various events and vacations which had a lot of overlap, but not 100% overlap.

This meant I needed to examine two large collections of photos and copy all of the non-duplicate photos from one to the other. And I couldn't rely on file names or paths at all, because my wife is good about renaming and organizing her photos, while I am not. So I whipped up a PowerShell script to gather the SHA-1 hashes of every file; by comparing them all, I could find and ignore the duplicates. It's not perfect - it'll only find pictures which are exact duplicates. If my collection has the original and my wife's collection just has the "red-eye reduction" version, we'll end up with both in the final collection. But it considerably reduced the amount of de-duplication work we have to do by hand.

Here's the function which actually gathers all the photo data for a folder (and all its child folders):

function Get-PhotoData {

    $results = @()

    $files = Get-ChildItem $path -Recurse -Filter *.jpg 

    $total = ($files | measure).Count

    $files | % {$i=1} {
        Write-Host "Processing $_ ($i of $total)"

        $props = @{
            Name = $_.Name
            Path = $_.FullName
            Size = $_.Length
            Hash = (Get-FileHash $_.FullName -Algorithm SHA1).Hash

        $results += (New-Object PSObject -Property $props)


I ran that function against my wife's photo collection (which was effectively our master collection) and my own:

$master = Get-PhotoData -path $masterPath
$toMerge = Get-PhotoData -path $toMergePath

In theory, I could then have used Compare-Object to figure out which items in my collection were safe to delete (i.e., they already existed in my wife's collection):

$safeToDelete = Compare-Object -IncludeEqual -ExcludeDifferent -ReferenceObject $toMerge -DifferenceObject $master -Property Hash -PassThru | Select-Object -ExpandProperty Path

This would give me a list of paths to photos in my collection which had a matching SHA1 hash to a photo already in my wife's collection.

Or, I could find the list of items in my collection which were missing from her collection:

$toMove = Compare-Object -ReferenceObject $master -DifferenceObject $toMerge -Property Hash -PassThru | ? { $_.SideIndicator -eq '=>' } | Select-Object -ExpandProperty Path

Moving each item in that collection would then be easy:

$toMove | % {$i=1} {
    Write-Host "Moving $_ ($i of $total)"
    Move-Item $_ "[destination path]"

For small enough collections, this works great. But if you've got a large enough photo collection you might start running into performance problems with Compare-Object. If that's the case, with a little extra effort and a little bit of Python you can figure out your $safeToDelete list much faster. First, we dump our photo data to a couple of files:

$master | Select Name, Path, Size, Hash | Export-Csv -NoTypeInformation "master.csv"
$toMerge | Select Name, Path, Size, Hash | Export-Csv -NoTypeInformation "toMerge.csv"

Now we throw together a quick Python program using pandas to read in the two data sets, merge them into a single data set by matching on the file size and hash, and dump the output to another file:

import pandas as pd

# Read in our email data file
master = pd.read_csv('../master.csv', header = 0)
toMerge = pd.read_csv('../toMerge.csv', header = 0)

both = pd.merge(toMerge, master, on=['Size', 'Hash'])

The new .csv file will have columns 'Path_x' and 'Path_y'; since we had toMerge as the first parameter to merge, Path_x is a list of all the files in that collection which can be deleted. More Python-savvy folks than me can probably handle the deletion straight from the Python script, but I just did it with PowerShell:

$toDelete = (Import-Csv .\safeToDelete.csv).Path_x

$total = ($toMove | measure).Count

$toDelete | % {$i=1} {
    Write-Host "Deleting $_ ($i of $total)"
    Remove-Item $_ 

Of course, don't go running any of this code or deleting any files until you've backed your folders up somewhere safe; if you make any mistakes (or any of my code is totally broken), you'll want a safety net in place.

How Long Would It Take To Read All My Email?

This is part of a series on mining your own Gmail data.

For this post I want to tackle a fun question: how long would it take to read all of my email if that's all I did, 24/7? It's one of those questions that should interest anyone who's concerned about information overload or is looking to pare down their information consumption: "Just how much of my time is theoretically committed to my inbox?"

First, the obvious: nobody actually does this. No one actually reads every email they receive from start to finish (as anyone who's dealt with email in a corporate environment knows all too well). Most of us have filters (both electronic and mental) set up to glean the info we need and skip the rest.

And I'll bet that a lot of email is written without any expectation that the whole thing will be read; the author may be well aware that different portions of the email are relevant to different recipients, or that the email itself will only be interesting to a subset of the mailing list (e.g., many marketing emails).

So it's not the one super-relevant data point that should make people completely re-think their information consumption habits or anything like that. But it is fun to think about, and as one data point among many others it might prove interesting or useful.

On to the fun part - actually coming up with a number!

Like most people, I'm getting new emails all the time. So technically I should be taking into account all the new emails I receive while I'm still reading through my old ones. But that's hard, so I'm not going to bother. Instead, I'm just going to assume I've stopped getting emails at all while I'm reading. Which means that getting a basic number is easy - I just have to count all the words in all my emails, divide that by the number of words per minute I read, and I've got the number of minutes it would take to read everything.

The first thing I need to do is go back to my PowerShell script and pull in the body of each email. This is where we hit the first snag - HTML emails.

For doing word counts, I really don't want to look at HTML emails, because there's a ton of junk in there which a human won't be reading. Luckily, most email clients which send HTML emails also include a text version; in those cases, we'll just extract that text portion of the email and ignore the HTML. Unfortunately, this isn't always the case; when there's not a text version available, we'll just have to get the HTML and figure out how to deal with it later.

As usual, MimeKit will be doing most of the work. This version of the script is pretty similar to our previous ones, except that we have to loop through the possible body formats for each message to figure out which formats are available. We always check for the 'Text' format first, because that's the one we really want. If that's not available, we run through the others until we find one that works.

The relevant changes are the hash of the possible formats, which we use for iteration and for tracking the number of emails of each type:

$formats = @{
    [MimeKit.Text.TextFormat]::Text = 0; 
    [MimeKit.Text.TextFormat]::Flowed = 0;
    [MimeKit.Text.TextFormat]::Html = 0; 
    [MimeKit.Text.TextFormat]::Enriched = 0; 
    [MimeKit.Text.TextFormat]::RichText = 0; 
    [MimeKit.Text.TextFormat]::CompressedRichText = 0

And the section where we determine what the actual format is and store it:

    $bodyText = $null
    $actualFormat = $null

    # Run through all the enumeration values
    # The pipe through sort ensures that we check them in the enum order,
    # which is great because we prefer text over flowed over HTML, etc.
    $formats.Keys | sort | % { 
        # try each Format until we find one that works
        if($actualFormat -eq $null) { 
            # Try to get the body in the current format          
            $bodyText = $mimeMessage.GetTextBody($_)
            if($bodyText) {
                $actualFormat = $_

    if($actualFormat -eq $null) {
        $unknownFormat += 1;
        $actualFormat = "Unknown"
    } else {
        $formats[$actualFormat] += 1;

You can find the full script here.

A couple of notes:

  1. This isn't perfect; sometimes MimeKit can't really figure out what the format is. For example, I have some Skype notification emails which MimeKit thinks are HTML only, but are in fact text. I'm not sure why MimeKit gets confused (probably incorrect headers in the original emails), but out of about 43,000 emails only a couple dozen seem to have issues, so I'm not going to worry about it.
  2. In all of my emails, the only two formats returned were Text and HTML. This might have something to do with what Gmail supports; I've seen some posts that suggest Gmail doesn't support Flowed, though those may be outdated. In any case, I'm only really dealing with Text and HTML in my word counts.

Once we've got the data, we can load it up in pandas and do some counting. Doing a naive count of the words in the plain text emails is trivial; we just define a method that uses Python's split method with None as the delimiter argument, and then look at the length of the returned list. Here's what textWordCount looks like:

def textWordCount(text):
    if not(isinstance(text, str)):
        return 0

    return len(text.split(None))

But the HTML emails are problematic because most of the content is markup that the user will never actually read. So we need to strip all that markup out and just count the words in the text portions of the HTML. To do that, we create another method which parses the HTML email content using the amazing Beautiful Soup library, strips away the style, script, head, and title parts, and extracts the text from what's left using get_text(). Once we've got the actual human-readable text, we can run it through our usual word counting method:

def htmlWordCount(text):
    if not(isinstance(text, str)):
        return 0

    soup = bsoup(text, 'html.parser')

    if soup is None:
        return 0

    stripped = soup.get_text(" ", strip=True)

    [s.extract() for s in soup(['style', 'script', 'head', 'title'])]

    stripped = soup.get_text(" ", strip=True)

    return textWordCount(stripped)

I took a couple of online tests to get an idea of how fast I read and came up with 350 words per minute. With that bit of data, we can now add some more columns to our data and figure out the total time to read all the emails:

def wordCount(row):

    if(row['Format'] == 'Html'):
        return htmlWordCount(row['Body'])

    return textWordCount(row['Body'])

averageWordsPerMinute = 350

# Count the words in each message body
emails['WordCount'] = emails.apply(wordCount, axis=1)
emails['MinutesToRead'] = emails['WordCount'] / averageWordsPerMinute

# Get total number of minutes required to read all these emails
totalMinutes = emails['MinutesToRead'].sum()

# And convert that to a more human-readable timespan
timeToRead = humanfriendly.format_timespan(totalMinutes * 60)

The full script is here, if you're playing at home.

Running that against all of my Gmail gives me:

>>> timeToRead
'2 weeks, 6 days and 18 hours'

So if I sat down and read at my fastest speed 24/7 for three weeks straight with no breaks, no sleep, and never slowing down, I could finish reading every word of every email I've ever received in my Gmail account. If I only read them 8 hours a day, it'd take me about 9 weeks to finish.

That's actually less than I expected, though "two whole months of your life spent just reading your email" is a still a bit sobering.

Sobering enough that I'm not going to try to compute this for my other four email accounts, anyway.

Mining Your Gmail Data - Part 6

First off, let's take a look at the second question that came up at the end of the last post: ignoring the Media Type (the 'application/', 'video/', etc.) from the MIME type.

That turns out to be pretty easy - the script from last time already collected that data, because MimeKit already made it available. We just need to adjust our pandas script to group on 'MediaSubtype' instead of 'MimeType':

types = notFromMe.groupby(['MediaSubtype'])

Attachment Types by %

That cleaned things up a lot. But we still have the second question from the last post: what's behind octet-stream?

Application/octet-stream is basically the generic binary file option; most likely the original client which uploaded the file didn't specify the type. But we can make an educated guess about the type based on the file name extension, where we have it. So we'll write a quick function which takes a row of data and, if the Media Subtype is 'octet-stream', returns the file name extension from the FileName column:

import os.path


def filetype(row):
    if not(isinstance(row['ContentTypeName'], str)):
        return ''
    if row['MediaSubtype'] == 'octet-stream':
        return os.path.splitext(row['ContentTypeName'])[1]
    return row['MediaSubtype']

We can run that function against our data and put the results in a new column which we'll call 'FileType':

notFromMe['FileType'] = notFromMe.apply(lambda row: filetype(row), axis = 1)

Now, instead of grouping by MediaSubtype, we just group by FileType. This isn't perfect - some of our data is getting discarded because there's not enough info between Media Subtype and FileName to figure out what kind of attachment it is. But the data is mostly good, and gives us a much more useful chart:

Attachment Types by %

I'm also running this chart with a threshold of 0.02 for the 'other' section, to clean up the less-frequent file types. The whole script can be found here.

So, if I'm looking to downsize my Gmail backup, I should probably concentrate on JPEGs, videos (wmv and mpeg), and PDFs.