File attachments in email marketing
At Boomerang, we get a lot of people who don’t fully understand the ramifications of file attachments including when and how to use them. This blog article will discuss how to properly utilize attachments in email messages.
Size considerations
When sending emails, you want to think about the size of the email message. The larger the message, the longer it takes to open and the more frustrated your user may become having to wait for it to open. If the recipient is reading the mail using IMAP or MS Exchange, the attachment may have to be downloaded before it can be viewed. This download process can either slow down the mail client or tie up the client until this download process has completed.
So, you always want to consider how big your attachment is before you send. For example, PDF files are common attachment types. But, attaching the file isn’t always the best way to handle a large file. The question you may be asking is, “How large is too large?” If the file is bigger than 50-100k bytes, then it’s really too big to be attached. With that in mind, never try sending 1-3 megabyte sized attachments. While this size may be small enough to fit under many email hosting providers 5-10 megabyte limits, it still consumes mailbox space. If the user has a quota that they must remain under, sending 1-3 megabyte sized attachments might be enough to fill up their mailbox. Instead, use a hosted link for large files.
Small nimble email
You want your messages as small as you can make them and still contain all of the content you need. So, why would you want to bloat an efficient HTML email with a huge attachment? There’s really no need for this. Instead, for files that need to be referenced, simply host them on a web server and use a link to allow recipients to easily download and open the files.
The only recipients that may have issues with this technique are those who don’t have ‘always on’ Internet. Although, at this point in time, I’m not sure who that might be. But, if you know that most of your recipients read their emails offline, then an attachment might be a better option.
Attachment bloat
When a binary file gets attached to an email message, this file is encoded into base 64 MIME format. This format is an ASCII (text) based format that’s suitable for text based transfer. This encoding process expands the binary anywhere between 20-40% larger than the original binary file. So, if the attachment is 50k, it may end up making the email message between 80-100k after encoding.
For some users who pay for bandwidth based Internet service, sending large attachments may consume more of their bandwidth than it needs to. So, in this case, it’s better to use document hosting over attachments. You will need to review your recipient list to determine if your recipients are constrained by their bandwidth.
Types of attachments
You can attach any type of file to an email message. The question isn’t whether you can, it’s whether you should. Again, you want your emails small and easy to read. By using an attachment, you’re guaranteeing that your email will open slowly and cause the reader to download large sized files. Just think about how you feel when you’re opening a 1 megabyte sized email?
For users on modem links (or other types of slow links) attachments really slow them down a lot. For the broadest audience for your list, you should always choose to make your email as small as possible.
PDF to HTML
If there’s really some information that you need to impart in the email, Boomerang can offer services to convert your PDF, PPT, DOC or other file content into an HTML viewable format. While this conversion process is manual, it can allow you to provide the same content to your audience with a much smaller email footprint (using jpeg images) than using an attachment. Boomerang can also convert many other file types into HTML format as well. If you really feel you must offer the Word, Excel, Powerpoint or PDF file to your recipients, then we can host that document for you.
Deliverability
As emails get larger and larger due to attachments, it’s more and more likely your email may be blocked because of the email size and/or specific attachment types. For example, you should never send attachments containing files with extensions .exe, .app, .dll, .chm, .com, .so, .o, a.out or any other type of format that could be considered executable. Executable formats are almost always blocked by filters. Some sites may even be blocking .doc (word) and .ppt formats because of exploits that have been previously been used. If you must send these types of attachments via email, then put them into a zip file that’s password protected. Password protecting the zip file prevents scanners from traversing into the file to look at the zip file contents. Although, you will need to send the recipient the password to open the .zip file.
Document Hosting
With email marketing, it is recommended that instead of attaching at all, that you use a document hosting service and make linked references to the files within your email marketing message. The user can then click the link and download the file as they need. When using hosted documents as a link, it’s an even better idea to put text like ‘[50k]‘ near to the link so the user has some idea of the file size before they click to download it.
For information on Boomerang’s Professional Services or document hosting services, feel free to contact sales at 800-779-7792.
Tags: attachments, document, email, excel, hosting, pdf, powerpoint, when not to use, when to use, word
Attaching long content will divert the attention of customers from reading it. Though your content is small, it must be interesting enough to attract the customers. If email marketing is not utilized properly then you will not fetch positive result.
In addition to the smaller footprint advantage of emails with links instead of hosted file attachments, there is another benefit: the file (e.g. PDF flyer) can be updated later without having to send a new eblastt to dispatch the changes.