File Size

Bluehost servers have a 50 MB attachment limit for the outgoing emails sent via SMTP and webmail. However, it is recommended that your total attachment size not exceed 35 Megabytes. The reason being that there are a number of factors that can determine how large of a file attachment you may send. These factors include:

• Your email is MIME encoded, which can increase the size of the email by 40%. This means a 35 MB file is the equivalent of 50 MB of space when MIME encoded for sending as an attachment.
• Any limits your email client has on attachments.
• Any limits the recipient's server. (for example, Yahoo! & Outlook.com all have a 25 MB limit. Gmail has a 50 MB limit.)
• How much free space is in the recipient's email account if their mailbox has a size limit. (If their mailbox is full, your message will be rejected.)

If you need to send larger files, it is recommended that you upload the file to your account and then email a link to the file.
 

Blocked Extensions

Here is a list of file extensions that are not allowed to be sent to any email address on the server. If someone attempts to send an email to a Bluehost account with an attachment that has one of these extensions, the email will be returned to the sender, and they will be notified that the attachment cannot be sent.

The reason behind this is because files with these extensions can be used to run a program that will install viruses or seriously damage your computer. Spammers and hackers often send emails with these attachments, trying to get users to open the attachment. Once it is opened, the computer is infected.

File extensions:

• bat
• chm
• cmd
• com
• cpl
• crt
• exe
• hlp
• hta
• inf
• ins
• isp
• jse?
• lnk
• mdb
• ms[cipt]
• pcd
• pif
• reg
• scr
• sct
• shs
• vb[se]
• ws[fhc])

Email Client Limitations

• Outlook 2013

  By default, Outlook 2013 and later versions have an attachment size limit set to 20 MBs. Microsoft has created an article explaining how to override this limitation: "Attachment size exceeds the allowable limit" error when you add a large attachment to an email message in Outlook 2013