Certain attachments are blocked by default to keep your inbox safe from malware. Commonly blocked file types include .pdf, .exe, and .src. On the other hand, .jpg, .gif, and .html files typically go through without issue. To ensure your email is delivered, compress sensitive attachments into a .zip archive before sending.
Another common cause is the file size. Attachments exceeding 10MB are often rejected. Webmail services usually enforce even stricter limits, sometimes under 2MB. A reliable solution is to upload your file to your website and share a link, optionally adding a password to restrict access.
