database/migrations/2016_11_28_201938_smtp_auth_optional.php
public function up()
    {
        Schema::table('smtp_config', function(Blueprint $t){
            $t->text('username')->nullable()->default(null)->change();
            $t->text('password')->nullable()->default(null)->change();
        });
    }
public function up()
    {
        Schema::table('smtp_config', function(Blueprint $t){
            $t->text('username')->nullable()->default(null)->change();
            $t->text('password')->nullable()->default(null)->change();
        });
    }
Run the migrations.

@return void