Bloated emails
May 25, 2023 3:09 PM   Subscribe

I know that an email message is always larger than what you'd think it would be given the amount of text and the size of the attachment. But why are they so bloated and bulked up?

A client likes to send large files back and forth. That's fine. They're InDesign files. The workflow is their choice, and for the most part, my email can handle them. But that doesn't mean it makes sense to me.

Today, for example, I had to return a file that was 19.7MB. I attached it to a message that had a few lines of text. I use Thunderbird. I'm on release 102.11.0. When I hit the send button, I got a message asking me if I really wanted to send a file that was 27MB. No, I'd really like to send a file that's maybe 20 or 21MB. I have no idea where or how all these extra megabytes are attaching themselves.

This is not a one-time event. This happens every time I have to send a message with files attached. And as I said in the question portion, I know that messages always add extra data and the size of the message is always larger than expected, but this really seems excessive. Can anybody explain what's happening? I'd love to know because I know there are people who can't receive large-sized messages, and I normally try to do what I can to avoid overstuffing their inboxes and causing bouncebacks, but there are times when I've got to send multiple files to people and I'd like to avoid the bloat.

(I'm composing messages in HTML. I've composed in plain text in the past, and it doesn't seem to make much of a difference when it comes to the extra size.)
posted by sardonyx to Computers & Internet (8 answers total) 5 users marked this as a favorite
I believe it has to do with how the binary file is encoded to a text, and inserted into the text-only email, which increases the size of the file. The email client on the other end then detects the embedded text file, and converts it back to binary.
posted by skwm at 3:22 PM on May 25 [8 favorites]

[I am an email postmaster. I am not YOUR email postmaster]

skwm has it right. Email wasn't particularly designed for binary data, and the encoding process that makes it possible to send over a text-only format tends to add about 30% overhead.

I generally recommend that files over 10MB or so be shared via a file storage service like Google Drive rather than over email.
posted by hanov3r at 3:49 PM on May 25 [6 favorites]

Best answer: To give a little more technical detail: the SMTP email protocol was designed as a protocol that uses 7 or 8-bit ASCII text, and there was no provision for embedding binary data there, and there is no safe way to just slap in binary data without really breaking compatibility. So, any binary data has to be converted to an encoding that can be represented safely in ASCII text, usually Base64 encoding, which adds about 35% overhead to the size of the email.

Seconding the recommendation to send large files through a file-sharing service instead. It will be much more reliable than sending files over email, especially anything over about 10MB.
posted by Aleyn at 4:02 PM on May 25 [9 favorites]

Someone with whom I collaborate on a small project likes to send files back and forth. He has gotten used to me storing 1 file in a Google account and sharing it, but was kind of stunned.

I use text in email as the default; it exposes me to slightly less useless stuff for sale, and I really like words.
posted by theora55 at 6:08 PM on May 25

Response by poster: As I said, this a client's preferred ways of managing their workflow, and as we know, the client is always right. Since my email system can handle it, I don't worry too much about it. The messages always go through. I just was hoping that there was a way to add slightly less bloat.

For stuff that isn't client-related, I'm also in the process of job hunting, and the application process for my profession means you have to send the CV and the cover letter and work samples. I've tried to get the work samples (PDFs) as small as possible (I've compressed them as much as possible) but some are still in the 5MB range if you add enough enough of them, they start to trip over the 10MB best practice limit. I'm not sending out links to file-sharing services for people to download as I know those aren't looked upon fondly by the hiring managers. I usually end up breaking up the messages, separating out the samples, but that causes other problems. (And no, I don't have a personal website with the work samples posted for [insert industry-specific reasons].
posted by sardonyx at 6:21 PM on May 25

In my last job, I was involved in sending and receiving huge files via FTP. It requires some setup, but is otherwise quite efficient. There are also some consumer-oriented services such as Dropbox. Also, cloud-based solutions like Google Drive.
posted by SemiSalt at 5:06 AM on May 26

Out of curiosity, are you compressing the files before you send them, for instance as a ZIP?
posted by ejs at 7:20 PM on May 27

Response by poster: I've started compressing some of the them. For years (this is a long-term client), they never compressed them, so I never sent them back compressed. Now, sometimes when then send them, they are compressed (sometimes they're not). I try to return them in the same manner they're sent to me.

I don't compress anything that I send out as part of a job hunt (because I know the type of people on the receiving end, and they're the type to ignore an application if requires more than one step to open and view it, and asking them to unzip files is a bridge too far).
posted by sardonyx at 7:28 PM on May 27 [1 favorite]

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