I deleted /etc/passwd yesterday and I am having problems with SendMail today

Solution 1:

To help avoid this problem in future, you can version control /etc, so in case of errors there you can always just revert to a previous version. The etckeeper package can help with this, by keeping track of permissions within the version control repository, and integrating commits into maintenance operations.

Solution 2:

The passwd file can be regenerated but with a lot of effort. Instead, you can use the following sample passwd file to at least make some of your system accounts work/

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
smmsp:x:511:511:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh
mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh
uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh
proxy:x:13:13:proxy:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
list:x:38:38:Mailing List Manager:/var/list:/bin/sh
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
libuuid:x:100:101::/var/lib/libuuid:/bin/sh
syslog:x:101:103::/home/syslog:/bin/false
messagebus:x:102:107::/var/run/dbus:/bin/false

As I have added the user smmmp to the passwd file, so your sendmail might work fine.

Also, look for /etc/passwd- file as well, as it is backup passwed kept by OS as well. it might be there.