EMAIL from friend... but apprently from plusnet???

[#1]

so i got  a email from a friend.....with a attachment (email had a different name then normale) but i thought nothing of it
i downloaded attachment did what i had to do ..... then i went to reply to the email.... i typed out email ...... clicked on send
then i get a email back from PN saying below (copy and pasted from email)
X-CM-Score: 0.00
X-CNFS-Analysis: v=2.1 cv=J66TsmXS c=1 sm=1 tr=0
a=BJaFPv9AyABFDM2hXLRoEA==:117 a=UoAHy/0mDQce5hgZfGnqdw==:17 a=0Bzu9jTXAAAA:8
a=R2hqwbujrt4A:10 a=dYCPD3cKDi0A:10 a=ihvODaAuJD4A:10 a=EBOSESyhAAAA:8
a=IC0aTQw04x4A:10 a=3Im67NWcawdT4qsm8ycA:9 a=QEXdDO2ut3YA:10
a=WAgf91G3XQQA:10 a=BVnJsomP4_QA:10 a=ZjQxqvoL9P72h3WePswA:9 a=_W_S_7VecoQA:10
X-AUTH: warbleeder:2500
Received: from warbleeder.plus.com ([81.174.173.133])
by webmail.plus.net
with HTTP (HTTP/1.1 POST); Sat, 09 Nov 2013 22:35:31 +0000
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="=_81b8c747f48b7c11b6d3fca5f7fd83cb"
Date: Sat, 09 Nov 2013 22:35:31 +0000
From: Ian Devonport <ian@warbleeder.plus.com>
To: memento <memento@memento.plus.com>
Subject: RE: TutorialB quests
Reply-To: <ian@warbleeder.plus.com>
Mail-Reply-To: <ian@warbleeder.plus.com>
In-Reply-To: <64e6c3f58d555e5960dbbdea164ac441@imap.plus.net>
References: <000301cedbe8$c4361f60$4ca25e20$@memento.plus.com>
<5a0be3887dcf9141b0ee5f073f1147ef@imap.plus.net>
<000301cedc00$ad5877d0$08096770$@memento.plus.com>
<9aeef590fabe675998dd1fe9c9b8b90b@imap.plus.net>
<000001cedc12$c081b0d0$41851270$@memento.plus.com>
<3e1d2014d430a71b85d7224576284f65@imap.plus.net>
<000301cedc14$4e30a2f0$ea91e8d0$@memento.plus.com>
<d82a20738676c93ce52078a0cc2bb1df@imap.plus.net>
<001101cedc16$9c554bf0$d4ffe3d0$@memento.plus.com>
<c45ef72b90f5986f828e1438bc817e94@imap.plus.net>
<000001cedc19$aad3e670$007bb350$@memento.plus.com>
<d2f8bf195d75b21de058a87fb34067fa@imap.plus.net>
<000901cedcbc$d9986a50$8cc93ef0$@memento.plus.com>
<f88fb75b1b2b0abafcf58caa156a50cf@imap.plus.net>
<64e6c3f58d555e5960dbbdea164ac441@imap.plus.net>
Message-ID: <a1d6bc8b76b8bc3d55a40ab6b61199de@imap.plus.net>
X-Sender: ian@warbleeder.plus.com
User-Agent: Roundcube Webmail/0.7.4
X-Originating-IP: [81.174.173.133]
--=_81b8c747f48b7c11b6d3fca5f7fd83cb
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=UTF-8
so my question is why has plusnet told me the email has come from memento@memento.plus.com instead of my friends email?
P.s Could this cause a delay in me recieving the emails?

[#2]

Not sure but you might want to "fudge" the email addresses slightly so the spambots and crawlers don't cache your addresses and start sending you more junk !

[#3]

Is mem*@mem*.plus.com not your friends email address ? Maybe he is using it to send out emails but receiving them from a different account ?

[#4]

ahh im assuming hes with plusnet too!
im running a server andi met him on forums as hes also a server dev and wel help each other out and exchange files by email
i just checked email and his is listed as r**@mem****.plus.com
but when he sent me the mail in question half of his email was missing :S and i couldnt reply to said mail