How many files can I send at once? XenVoice December 18, 2018 15:10 Updated You can send up to 5 files at a time (the size of each file can be of up to 5 MB). The total size should not exceed 25 MB. Related articles Can I send faxes to multiple numbers? What are the supported Fax file types and file size? How to send a fax with XenFax? How do I integrate XenVoice with WhatsApp, Slack and Skype? How to create a Fax cover letter?