Manage e-mail attachments

There are things to keep in mind when it comes to e-mail attachments.
For security reasons, some file formats can't be sent as attachments in e-mail.

Maximum size of e-mails

The maximum size of an e-mail is 25 MB. This applies to both the e-mail size and the attachment size combined.

The maximum size also applies to e-mails sent via the case management system Edge as it reads e-mails via Exchange.

If you want to send e-mails larger than 25 MB, you can share the attachments via OneDrive.
Read more about how to do this here: Share files and folders in OneDrive

Approved file formats in attachments

The file formats listed below are approved if you send them in an archive file (.zip or .rar-files for example).

Here is an example of different types of archive files: .zip, .tar, .tgz, .taz, .z, .gz, .rar

File formats that are whitelisted (approved):

*.M .*CPP *.JAVA *.patch *.JS *.MAT *.CXX *.H *.BS *.PRO *.txt *.c *.html *.m *.cpp *.java *.js *.mat *.cxx *.h *.bs *.pro

Non-approved file formats in attachments

You may not send or recieve the following file formats:

.ade, .adp, .bat, .chm, .cmd, .com, .cpl, .docm, .exe, .hta, .ins, .isp, .jar, .jse, .lib, .lnk, .mde, .msc, .msp, .mst, .pif, .scr, .sct, .shb, .sys, .vb, .vbe, .vbs, .vxd, .wsc, .wsf, .wsh

E-mails that contain any file format listed above will automatically be returned to the sender. For security reasons it is not possible to send an e-mail with these file formats at KTH even if they are in an archive file.

Excelfile containing macros might get caught depending on how the macro is interpreted in the automatic examination. This applies to filetypes .xls, .xlsx, .xlsm