How to email large attachments

I’m such an impetuous guy.

When I have an email to send with a large attachment I just want it to go through.  I don’t care how large it is, I don’t care if the file extension is valid; I just want the magic of the interwebs to flutter my email off to the intended recipient so I can go about my day.

But I also realize everyone isn’t so rash.  Some users are more circumspect than others and are careful to trim attachments before sending.  Calmer, more staid users, realize that email servers can only transfer files so big before they start coughing up errors.

So what’s the deal?  What’s the maximum attachment size for email?  Is there an easy way to send large attachments over email?

Today I’m going to answer both questions and equip you with the knowledge you need to easily email your large files!

Let’s go!

Let’s say I just returned from Georgetown Cupcake in Washington DC, and I want to share pastry and cake photos with my family.

The files are large because I took them in the highest resolution my Nikon offered.

For example, the photo below was over 5MB before I compressed it for this post.

So here’s the question:

Can I just drag a bunch of photos like this into Outlook.com or Gmail and expect them to arrive unscathed?

Well, that depends on a few things…

Emailing large files

Every email program out there, from Outlook to Yahoo Mail use a protocol extension called MIME which is just an abbreviation for Multi-Purpose Internet Mail Extensions.

Before MIME entered the scene in the early 90’s, emails were banal, pedestrian collections of black text on white backgrounds.

Emails were drab. boring and just plane ugly.

MIME augmented the Simple Mail Transfer Protocol, SMTP, and enabled email clients to support multimedia elements such as colorful HTML text and image attachments.

So when I fired off my cupcake photos to my Dad, the email actually took a circuitous path through multiple Mail Transfer Agents (MTA) before arriving at its ultimate destination.

The MTA is just software running on a computer that receives and forwards emails. Sendmail and Microsoft Exchange are popular MTAs that you’ve probably heard of.

Each MTA has to temporarily hold the message before forwarding it and each MTA is completely outside my control.  So even if my company or ISPs email server can handle 25MB attachments, if any one of the MTAs between my computer and the recipient’s have MTAs with smaller attachment restrictions, the message will be discarded.

So what’s the max attachment size?

Each Mail Transfer Agent can have its own size guideline but the consensus among IT professionals is that 10MB is a good canon to use for email attachments.  There’s no official documentation or standard for maximum attachment size; however, since most email vendors max out attachments at 10MB, 10MB is considered the email attachment limit.

So what are the implications?

Well, even though Gmail lets you send 25MB attachments, this is only germane for Gmail-to-Gmail communication.  The moment you send attachments larger than 10MB to people off the Gmail network you risk the recipient never receiving the message.

Fortunately the workaround is surprisingly easy: just click the blue Send using Google Drive button and you’ll be on your way to attachment nirvana.

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But what about Outlook.com (formerly Hotmail)?

Just for kicks, I tried to send a 24bit lossless Aersosmith song, Girls of Summer.flac which is about 80MB, but Outlook.com rejected me:

We can't attach your files because they exceed the 25MB limit.  To send these files, use OneDrive.

In both the Gmail and Outlook.com cases, the recommended way to send attachments between 10 and 25MB is to use Google Drive and OneDrive respectively.

But what is OneDrive?

OneDrive is Microsoft’s free file storage service.  It’s like a digital locker for your stuff – and the last I checked that locker is pretty capacious.

OneDrive lets you upload attachments up to a voluminous 10GB and gives you a prodigious 15GB of total space.

That should last you for some time.

Similarly, Google Drive gives you 15GB as well but I think it’s fettered to paltry 50MB uploads but I haven’t confirmed that limit (someone check me on that one).

Sending bigger stuff

If you need to send something larger than 25MB consider using Dropbox Links.

Dropbox Links is a great way to send a direct link to a Dropbox file without require the recipient to have Dropbox.  You can even restrict access to specific people set an expiration timer.

Alternatively, I know some users have had success with another web based application called Filemail.com.  This one has the advantage of not only being free but also requires zero sign-up to get started.  That’s right – no registration required.  In addition, you can include attachments up to 30 GB and they stay valid for up to 90 days.

I encourage you to check out the 1 minute video introduction on Filemail’s Youtube channel.

Outlook 2010 and 2013 email attachments

If you ever tried to send an email attachment larger than 20MB in Outlook 2013 or 2010 you might have seen this unseemly message:

Attachment size exceeds the allowable limit

or maybe this one:

The file you're attaching is bigger than the server allows.  Try putting the file in a shared location and sending a link instead.

Believe it or not this error is actually a good thing.  Since most ISPs don’t allow attachments greater than 10MB, Outlook is doing you a favor and saving you some frustration down the road.

By the way, since the 20MB isn’t a hard coded standard, the Exchange Sysadmin could technically lift the 20MB limit.  It’s literally just a matter of changing the Maximum send size property in the Transport Settings Properties box of Exchange 2013 – but it’s obviously discouraged since it only increases the chances of your message getting kicked back by an MTA.

One last thing I almost forgot to mention: even if Windows shows your attachment is exactly 20MB, it still may get rejected because MIME headers add to the final file size.  So if you absolutely must email an attachment greater than 10MB in Outlook 2010 or 2013, try to keep your message a few Megabytes below 20MB.

The Bottom Line

To play it safe, always keep your attachments less than 10MB; however, if you need to send something larger you can use Dropbox Links or Filemail.com.

Gmail-to-Gmail and Outlook.com-to-Outlook.com emails both have a 25MB maximum attachment size but remember: since sending to email addresses off those domains require the message to traverse multiple MTA’s so your attachment may get blocked.

The easiest way to send large attachments is to use OneDrive or Google Drive.  Both integrate seemlessly with the web browser and allow a commodious 15GB of space.  Moreover, they are both 100% free so there’s no reason I can think of to not use it.

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What creative ways do you use to send large email attachments?  I’m curious since I can only talk from my experience.

Please share with me in the comments below!