[spc476]

I wrote a greylist server ( http://www.x-grey.com/ ) and I arbitrarily capped emails at 108 characters. In testing, I collected 565,012 tuples (IP address, sender address, recpient address)---the longest in that testing corpus was 107 characters (15), the average length was 24.24 characters and the median was 23 (just checked now). Capping at 108 meant I could store two addresses, plus a IPv6 address, plus some timestamps in 256 bytes of memory (one feature of my greylist implementation---everything is stored in memory).

Over the year and a half it's been running, I have seen a few addresses exceed the 108 character limit (which isn't fatal as I do store such addresses, only the first 108 characters) and by few I mean "less than 1% of 1%". Bumping the record size to store a full 254 bytes (or is it characters? There is a difference) would double the memory consumption of the program for very little gain in return (but at least I have numbers to back up my position).