If you are emailing with InterForm400 you should make sure, that you are deleting the old emails. This can be done with the command: APF3812/CLRMAILLOG. The command has these parameters:

                          Clear Mail Log (CLRMAILLOG)

Type choices, press Enter.                                                                                       

Mimimum days old . . . . . . . . MINDAYS        120      
OutBox directory . . . . . . . . OUTBOXDIR      *ALL_____        
Reorganize physical file mbrs  . RGZ            *NO   

So as default the command will delete any email in the /apf3812mail/outbox directory older than 120 days. You can choose to store the outgoing emails in subdirectories in the outbox directory, so for this command you can also choose to only cleanup a certain subdirectory – or all. The reorganize option should be set if you have deleted many emails (or if you expect to do so with this call). The reorganization will remove any deleted records in the related InterForm400 data base files.
 
It is recommended to add a call of this command in the OS400 job scheduler (WRKJOBSCDE) to be run on a regular basis.
 
If you are using IBM SMTP the emails will only be stored temporarily in OutBox until they are sent.
 
If you have the save option activated when you create emails, then the emails are not only saved in the /apf3812mail/OutBox directory but also in the /apf3812mail/Log. The old emails saved in /apf3812mail/Log are not deleted with the CLRMAILLOG command, so you will need to delete the old emails here yourself.