Depending on the font in an email or a website, a lowercase “L” can look an awful lot like an uppercase I. Someone could try and fool a buyer into thinking that they are selling a valuable domain name that begins with the letter “I,” but in reality, it is really a lowercase “l.” They may look the same in some formats, but obviously one would be a word and the other would not spell anything.
It seems like most domain name marketplaces and auction platforms make an effort to ensure there is little confusion when it comes to the letters in a particular domain name. Listing the domain name in all lowercase letters is helpful, and having the option to view the uppercase version is helpful as well. I think most of the major platforms and marketplaces don’t allow sellers to interchange upper and lower case letters. This isn’t foolproof because some people may not think the l is a L even though the letters are lowercase.
When it comes to email negotiations though, it is possible these two letters could be interchanged