Do the “SendStatus”, “LastSent”, and “#” columns need to be the first 3 columns?
No. CustomMailer will insert “SendStatus” as the first column if you don’t have a “SendStatus” column, and it will insert “LastSent” and/or “#” in the next position(s) if those features are enabled in Preferences. However, if you reorder these using the Edit Mailing List Column menu command, or insert and/or rename columns so that they appear in different locations, or if you have these names in other positions in your mailing list when read in, CustomMailer will find, use, and preserve them in those locations.