The most common reason for this by far is the use of anti-spam measures. Especially those systems which require the sender of an e-mail to manually verify a message. The second most common reason for not getting e-mails is that the e-mail address entered does not exist, double check those e-mails! Finally, certain email services (such as msn and hotmail) seem to be better able to receive our messages to you if you have donotreply@gravatar.com added to your contacts already.

We cache your gravatars for periods of time, which means that your new gravatar will take effect after the old one expires from the cache. The reason we do this is to be able to serve your (and indeed everybody's) gravatar images much more quickly and reliably.

Usually the reason for this is a common error in making image links on the originating site. Click here: http://en.gravatar.com/support/check to double check your gravatar.') If your image comes up correctly, then you may want to direct the site in question to the "I'm trying to implement gravatar for my site, and some peoples gravatars aren't displaying!" FAQ entry below.

This is a pretty concise guide on clearing your cache no matter what browser you use: http://kb.iu.edu/data/ahic.html.

Basically your computer (in an attempt to make things faster for you) keeps copies of things (your avatar image, for example) on your computer, and the next time you request one of those things instead of getting it from the internet it gets that local saved copy. in this case you don't want the saved copy, you want the new one from the internet. Thats what clearing your cache does... it deletes all the local copies of things that your browser keeps around.

I'm sorry, we currently don't delete accounts. If you remove all the images from your account, however, this simulates your account being deleted as far as the outside world is concerned

Send an e-mail to support at gravatar dot com

The most common cause for this issue is the e-mail address case. Gravatar uses lowercase e-mails exclusively for serving content, so an md5 hash of FOO@BAR.COM is not the same as foo@bar.com. In php, try md5(strtolower($email)); (adapt for other languages) The gravatar verification check tool might prove useful.

MD5 is plenty good for obfuscating the email address of users across the wire. if you're thinking of rainbow tables, those are all geared at passwords (which are generally shorter, and less globally different from one another) and not email addresses, furthermore they are geared at generating anything that matches the hash, NOT the original data being hashed. If you are thinking about being able to reproduce a collision, you still don't necessarily get the actual email address being hashed from the data generated to create the collision. In either case the work required to both construct and operate such a monstrocity would be prohibitively costly. If we left your password laying around in the open as a plain md5 hash someone might be able to find some data (not necessarily your password) which they could use to log in as you... Leaving your email address out as an md5 hash, however, is not going to cause a violent upsurge in the number of fake rolex watch emails that you get. Lets face it there are far more lucrative, easier, ways of getting email address. I hope this helps ease your mind.

If you’re worried about what transparent PNG images look like for your IE visitors, I would recommend taking a look at this handy Transparent PNGs in Internet Explorer 6 page which offers an explanation, information on workarounds, and a drop-in javascript which will work for all the images on a page.