PHP-MySQL Email type Messages sender's name storing debate -

i'm working on building database messaging system work more email rather chat.

i've come across little debate whether should allow sender's name static or dynamic.

what mean is, should save current user's display name when message sent or name pulled user's personal details? means if user changes his/her display name, take effect on every message ever received others.

in project, not forsee users changing display names bound happen , not sure approach take.

the thing comes mind if dynamically, confusing messages of given user , not find them because name has changed.

any pointers?

this come down how want application function. both points raised valid.

if implementing feature believe go route of having usernames change dynamically. save past aliases of each user in separate table, , have page/widget display them. example, when user opens message x user hover on name , past aliases show in modal. or click on name, directed user's profile have link click on took them page showed past user aliases.