Handout on how to handle attachments
On this page, you will find information on the general handling of attachments, blocked attachments, and alternatives to sending e-mails with large attachments or amounts of data.
Handling attachments
E-mail attachments can contain potentially dangerous files (e.g. malware). Check especially with e-mails that seem suspicious or unusual to you whether it is a legitimate e-mail and the correct attachment.
In case of doubt, ask the sender of the e-mail. How to recognize suspicious attachments and e-mails and how you should proceed in dealing with them can be read in the article Suspicious E-Mails.
Especially attached files with the extensions .exe, .msi, .bat or .zip, .rar can be potentially dangerous. But other file types containing macros, for example .doc, .docx, .pdf can also be used.
In order to minimize the risk potential of attachments, RWTH filters out files that are recognized as dangerous or contain potentially dangerous macros in advance. Information on this can be found in the article E-Mail Macro Filtering.
Even with filtering, not all suspicious files can be found. Before saving / downloading or opening attachments, you can additionally check them via antivirus software or a site like Virustotal.
Sending large amounts of data
If you want to send large amounts of data with file attachments via e-mail to multiple addresses or distribution lists, this can quickly lead to problems:
- Depending on the number of addressees (distribution lists often contain thousands of e-mail recipients), the data traffic can be very high.
- Well-known e-mail providers generally allow a total e-mail size of 20MB to 40MB (receiving & sending)
- At RWTH Aachen University, the maximum e-mail size is 25MB (e-mail text + attachment) to ensure that e-mails can be delivered inside and outside of RWTH Aachen University.
- Mailboxes usually offer only limited storage space. They are not suitable for storing large files.
It is therefore advisable to make files available via alternative routes. For example, you can make files available via a download link to a data storage system. In addition to the points mentioned above, this can also lead to more security in communication.
If, for example, you are already using data storage services when working on collaborative projects, these often offer integrated solutions for sharing data.
Especially when handling documents, the use of a corresponding service is recommended, as this ensures that all addressees always access the most current version of a document and that multiple versions are not circulating, e.g., in an e-mail attachment.
As alternatives at RWTH, you can use the following options:
