Why am I seeing double entries in maillog for each email sent?

Question

Can anyone explain to me why there are two similar entries of "from" and "to" in maillog every time an email is sent?

2013-01-29 12:12:42 sendmail 2770 r0T4CfFe002770: from=user, size=265, class=0, nrcpts=1, msgid=<201301290412.r0T4CfFe002770@localhost6.localdomain6>, relay=root@localhost

2013-01-29 12:12:43 sendmail 2771 r0T4CgIp002771: from=<user@localhost6.localdomain6>, size=572, class=0, nrcpts=1, msgid=<201301290412.r0T4CfFe002770@localhost6.localdomain6>, proto=ESMTP, daemon=MTA, relay=localhost6.localdomain6 [127.0.0.1]

2013-01-29 12:12:43 sendmail 2770 r0T4CfFe002770: to=test@mail.com, ctladdr=user (500/500), delay=00:00:02, xdelay=00:00:01, mailer=relay, pri=30265, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (r0T4CgIp002771 Message accepted for delivery)

2013-01-29 12:12:48 sendmail 2773 r0T4CgIp002771: to=<test@mail.com>, ctladdr= (500/500), delay=00:00:05, xdelay=00:00:05, mailer=esmtp, pri=120572, relay=verifier.port25.com. [96.244.219.19], dsn=2.0.0, stat=Sent (message received)

Is there something wrong with my mail setting or is this the normal behaviour?

Answer 1

Usually, every mail an MTA (Mail Transfer agent) handles involve at least two distinct operations: It receives it from an external SMTP server or a MUA (Mail User Agent, like Thunderbird etc.) and it sents it, either to another SMTP server (relay) or an MDA (Mail delivery agent) that actually stores it and makes it available to MUAs, e.g. an IMAP server.

Since these are two operations, having two log file entries is entirely normal.

Answer 2

One is your mailer logging receipt of the mail from your local client and the other is it logging that it sent it to the destination. What you're seeing is quite normal.