Cannot allocate memory (errno = 12)

[net64]

my server went down this morning and my message logs were filled with messasges like theese:

relaylock: /var/qmail/bin/relaylock: Unable to connect to the mysql database, relay will work in closed
mode & white list will not work

smtp: fork failed: Cannot allocate memory (errno = 12)

service smtp: too many consecutive fork failures

pop3: fork failed: Cannot allocate memory (errno = 12)

Can anyone tell me what they think is going on and how to fix this?

Thanks

 

[net64]

more info

What I am trying to figure out is was this an internal thing gone awry or was it some kind of outside attack?

When I looked at my messages.1 log for
the previous day there are a ton of these messages...

warning: can't get client address: Connection reset by peer

My memory allocation seems fine now after restart, so I don't think that is the issue....

Also when looking in /var/log/secure I am seeing this message over and over with various addresses:

START: smtp pid=29824 from=61.11.57.93

Ever seen this problem before and how do I fix it?

Any Help is appreciated!!
My apologies for being new at this...