Describe the bug

The "-f" flag (Mailgun / Mail From Address) does not work

To Reproduce

Run:
$ update-ngxblocker -f FROM_ADDRESS -e TO_ADDRESS
[...]
mail: conflicting options

And the email is not sent.

Expected behavior

The email should be sent with the specified "from" address

Server (please complete the following information):

• Operating System:

• [X ] Ubuntu

• Specify Exact Version of OS:
  Ubuntu 22.04.2 LTS

Post output of uname -a here
Linux XXXXX 5.15.0-72-generic #79-Ubuntu SMP Wed Apr 19 08:22:18 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

Additional information

The problem is the that "-f" flag (at least on Ubuntu) calls the "mail" command with the "-f FROM_ADDRESS" option (function send_email), but the "-f" flag for the mail command is to specify a mailbox file. I was able to workaround this issue by using the "-a" (add header) specifying the from address as per the following diff:

275c275
< 			cat $EMAIL_REPORT | $mail_path -f "$MG_FROM" -s "Nginx Bad Bot Blocker Updated" $EMAIL
---
> 			cat $EMAIL_REPORT | $mail_path -a "From: $MG_FROM" -s "Nginx Bad Bot Blocker Updated" $EMAIL