The file names and sizes of attached files are putting more and more e-mails incorrectly into ‘quarantine’ by the increasingly strong spam and virus filters necessary to try to keep e-mail clean. While the newer versions of word processing programs make it fast and easy to give files long, complex filenames, email servers and filters are not as happy with these names.
Here are some tips for everyone, to help keep e-mail and list messages flowing freely:
- Keep file names under 50 characters
BAD: white-paper-version2-for-review-by-association-board-and-key-members-for-review-during-23april-session-on-hill-by-safety-committee-for-reformbill810-H692-1927.pdf
GOOD: white-paper-safety-v2-23april2010.pdf - Do not use spaces in filenames
BAD:white paper safety v2 23april2010.pdf
GOOD: white-paper-safety-v2-23april2010.pdf - Do not use periods in the filenames; make sure that the only period (.) is between the file name and the document-type extension
BAD: ShowDoc.aspx.pdf
BAD: ABC.OPPOSE.BPA.BAN.pdf
BAD: S51089.managers.amdtx.pdf - Do not use special characters in filenamesThese don’t always cause issues, but best to avoid them just in case.
BAD: a/bc!@#$%^&*()_.doc
BAD: annualmeeting@hilton-brochure.pdf
BAD: smith&jonesbranding.doc - Do not attach large files.
Unfortunately, there is no explicit guide here.
1MG is probably fine.
5MG should be fine.
10MG is probably not fine.The key problem is that attachment size is only one piece of the email size. The total ENVELOPE size (including attachment(s), body, headers, etc) is larger, and that is what email servers care about. Depending on how many separate attachments, line breaks, headers, or other elements are in the message, your entire envelope size can be 20%-40% larger than the attachment size. The exact size can vary enormously, especially since mail systems all behave a little differently.
Example: A 7.3MB PDF attachment produced a 10.1MB total message size; a different type of file attachment would have produced a slightly different total message size.
When you go above the size limit allowed by a receiving email server, you run the risk of the receiving server blocking it, or your IP being blacklisted by the Spam filters that monitor messages. For most MatrixMaxx clients, we will only route an email that is up to 10MG in total envelope size. (So, anything above a 5MG attachment might end up being too large and we will block it from sending out.)
However, think about how many of your users are using smart phones or small mobile devices to check email, and you may want to keep filesize even lower and instead link to documents that are housed on your websites and in your CMS pages. Large documents can also be conveyed using file transfer services like DropBox. - Make sure attachments will make it through the filters.
Do not attach executables or code!
BAD: runme.exe
BAD:index.aspx
And, Other types of files may cause issues, too … so be careful!