Occasionally, all ISP experience gliches that prevent your emails being sent.
If this is happening constantly it is worth checking whether your email address is being blacklisted. If you are sending multiple emails out, it may be that you are being blocked for potential spamming by one or more of the many spam protection services.
To check this do the following:
- Find out your Ip address – visit www.whatsmyip.org
- Entering the IP address here – http://whatismyipaddress.com/blacklist-check
