"There are, of course, limitations on the size of email messages. The details are explained at
https://helpdesk.ugent.be/email/attach.php. More information can be found at
https://mailtrap.io/blog/email-size/.
The email or list-server is intended as a means of mass communication, a so-called message pump; it is not intended for file sharing. Therefore, attachments on that platform should be avoided or kept to a minimum.
There are a few strategies to work around this limitation:
1. Increase the email limit: This is not effective as the limiting factor is often the email client (e.g., Outlook) or the available bandwidth when the email is being read (e.g., via GSM on an older device or slow connection). In short, just because your email client and connection can handle it doesn't mean the recipient's can.
2. Reduce the size of the email and its attachments. Here are some options:
a. The email message itself: For example, consider the size of the images in the mail footer (do you really need them? can they be in plain text?)."
b. attachments:
- If you really need them, can you provide a reference to a location? It's better to share a link to a file available on the internet or intranet rather than sending the file itself.
- If the attachments are not available at a location, make arrangements to store them: upload the material to a website (where the recipient may or may not need to log in) or save it to a shared (One)Drive (which is essentially a type of website). If it's internal to UGent, it can also be stored on a shared network drive.
- If it must be sent as an attachment, limit the size:
-- Compress the attachment(s) into a zip file or similar format.
-- Specifically for images and photos:
When placing them in a zip file, the result is often disappointing because the files already use some form of compression.
To reduce their size (in bits), it's best to use graphic software (or a website that can do this). Previously, the guideline was to reduce images to 72 dpi, but nowadays, it can be slightly more. Since this may seem abstract, a guideline like limiting the width in pixels can be used, for example, 1000 pixels wide is sufficient.
This can easily be achieved using software like IrfanView or similar tools (also in batch mode, processing all files in a specific folder at once).
Photo websites (Flickr, Google Photos, etc.) handle this automatically: when you upload photos there, they offer various versions depending on what the recipient (in this case, a web browser) can handle.
Another option is to change the format; this is what major internet players like Google, Netflix, and Facebook do (as they want to control their bandwidth usage).
Newer formats are increasingly better in this regard. Look into AVIF (
https://en.wikipedia.org/wiki/AVIF) and others; here's an overview:
https://graphicmama.com/blog/best-new-image-formats-2021/
If your attachment is still too large after these actions or if your location cannot handle such large files (e.g., a web share at UGent has limitations, and files larger than 1 GB might pose a problem), you'll need to resort to specialized sites. For UGent users, Filesender is available:
https://www.belnet.be/en/services/identity-mobility-federation/filesender
Note well:
- Reducing the size or resolution of images is not a good idea when it comes to high-quality print work (consult your pressman for advice and solutions).
- If you put something on a web location, make sure that security is in place. All zip programs have the option to work with a password. Filesender also offers this feature.
Encrypting files before sending them is recommended if the material is confidential. Keep in mind: this will increase the file size again...
Note well 2: Email attachments are an ideal vehicle for phishing attempts. Our infrastructure to prevent phishing and similar threats will inspect every email and all attachments, even if they are packed in a zip file. These software solutions go to great lengths in their inspection process. For example, a text file will be unpacked in a so-called sandbox (a virtual PC), and it will be checked to ensure that opening that text file doesn't trigger any other actions. While this process is fully automated, you can imagine that checking all attachments passing through UGent can be time-consuming. This time consumption could result in slower email delivery. (If the recipient is outside of UGent, a similar process may occur on their end.) Hence, this is another reason to avoid using attachments.
Created: 27 July 2023
Last updated: 3 March 2025 07:49:25