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 F.A.Q. about Advanced Maillist Verify |
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1.Where do nonexistent addresses come from and what kinds
of them are there ?
There are many reasons of nonexistent address appearance: the user can
change his Internet Service Provider (ISP) and his e-mail consequently;
the organization can buy the first level domain, for example myorganization.org,
and previous domain myorganization.myisp.com stop to exist. The e-mails,
for example, info@mailutilities.com,
contain two parts - the domain mailutilities.com is written after sign
@ and the mailbox support - before sign @. Typically, there are above
20% of nonexistent addresses in mailing list of a one year old - that
are addresses at nonexistent domain. There is no mail server connected
with such e-mails in Internet and it is impossible to send message to
such address - just nowhere to send. The other 80% are the addresses with
correct domain, but with nonexistent mailbox. Such addresses appear when
his owner changes his job, study or ISP. Advanced Maillist Verify can
determine both types of nonexistent addresses.
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2. Why does AMV say that the address is existent, but
my message can not be delivered ?
AMV can determine 80-90% of nonexistent addresses as it is said in program's
help. Other 10-20% can not be defined without sending message in principle
because of special mail server setting. Two types of such settings are
described below.
Network with internal mail server. Example of such network is
shown in picture 1. When you send message to address john@anybody.com
from address yourname@yourisp.com
the message will get to mail server smtp.anybody.com through your provider
mail server smtp.yourisp.com. Mail server smtp.anybody.com is configurated
so that it receive messages for domain anybody.com without checking mailbox
and transfer message to internal server smtp.int.anybody.com for further
processing. Server smtp.int.anybody.com is not associated with mail domain
anybody.com in DNS, but it can be accessible through Internet.
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Pic.1. - Example of network with internal mail server.
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If you send message to nonexistent address mary@anybody.com
you will receive it back with remark like this ( here is only essential
part of return message ):
----- The following addresses had delivery problems -----
<mary@anybody.com> (unrecoverable error)
----- Transcript of session follows -----
... while talking to smtp.int.anybody.com:
>>> RCPT TO: <mary@anybody.com>
<<< 550 5.1.1 No such local user: mary
550 <mary@anybody.com>... User unknown
----- Original message follows -----
Received: by smtp.anybody.com with SMTP
id VAA06942; Mon, 19 Jul 1999 21:35:19 +0200
Received: from smtp.yourisp.com (194.186.29.1) by gd2ke1 via smap (V2.0)
id xma006930; Mon, 19 Jul 99 21:34:50 +0200
Received: from localhost (ppp8-dialup.yourisp.com [194.186.29.132]) by smtp.yourisp.com with SMTP
id WAA04675 for <mary@anybody.com>; Mon, 19 Jul 1999 22:34:45 +0300
The message from you was received by your provider mail server smtp.yourisp.com
and successfully transferred to server smtp.anybody.com as it follows
from message path (Received). Error was happen during "talk"
between servers smtp.anybody.com and smtp.int.anybody.com. AMV had made
error when decided that address mary@anybody.com
is existent, because mail domain anybody.com is associated in DNS with
server smtp.anybody.com that receive all messages for domain. Program
don't know that it is necessary to check smtp.int.anybody.com, but not
smtp.anybody.com. And what is more, internal mail server may be inaccessible
through Internet - such method is often used to protect mail server from
hacker's attacks.
The second typical situation. In some organizations there is a
special officer or even whole department for mail service. In this case
mail server also receives all messages for domain, but the messages to
nonexistent box are transferred to that officer, usually to address postmaster@myorg.com.
He must send message to the really recipient - for example, the message
with nonexistent address j.smith@myorg.com
send to john.smith@myorg.com.
This work may be done by "clever robot" which send to you answer
that "address j.smith@myorg.com
doesn't exist, may be you want to send message to John R. Smith john.smith@myorg.com
or to Jane M.Smith jane.smith@myorg.com,
otherwise apply to our support service support@myorg.com".
You can not be convinced that address j.smith@myorg.com
doesn't exist without sending message because mail server receives messages
for all addresses within domain.
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3. Which input/output formats are supported ?
The program supports two formats of mailing list. The first format is
a simple text file each line of which contains one e-mail. Address can
be written, practically, by any way. When you save results, AMV write
out address from input file to output one saving original line format:
check_email@bolton.starnet.com
check_email@bolton.starnet.com - Nick Bolton
<check_email@bolton.starnet.com>
<Nick Bolton> check_email@bolton.starnet.com
Nick Bolton <check_email@bolton.starnet.com>
Nick Bolton check_email@bolton.starnet.com
"Nick Bolton" check_email@bolton.starnet.com
If your mailing list has a special format - just mail us and its support
will be implemented in program. But any program, for example Outlook Express,
has a possibility to export its format to text and import it back.
The second format is CSV-file (Comma Separated Values). It was made
special for Outlook Express users. You can export entire address book
to CSV-file. Then load file to AMV, save result, erase address book in
Outlook Express and import it back from checked CSV-file. It is recommended
to create a backup of address book. A person can have a number of e-mails
(e.g. home and working), but only one e-mail is checked for each person
in CSV-files.
You can use also a special address syntax MAILBOX@[SMTP-SERVER]. For
example, write alex@[smtp.enet.ru] to check box ðlex at server smtp.enet.ru.
Server can be specified by domain or IP-address, tcp-port can be indicated
through colon (by default - 25).
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4. What is the optimum number of threads for checking
?
The program can check from 1 to 99 addresses at one time - each address
is checked by separate program thread. It is recommended to use 15-20
threads to work through 33.5k modem. Further increase number of threads
in this case don't result in productivity increase, but even decrease
it because of modem channel overloading. In case of high-speed Internet
connection increase number of threads till maximum may result in DNS-server
overloading, and the most of checking addresses will be
marked as "Unknown" because of DNS-server refusals, although
your output channel is loaded only by 30%.
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5. Why many of my addresses was marked as unknown?
You set too large number of threads or Internet connection is not quality
and the program can not connect with mail servers for address checking.
There was only one exception in practice, when all checking addresses
were marked as unknown - provider carry out too "advanced" anti-spam
policy and prohibit users to connect with any mail server except its one.
If you are sure in quality of your Internet connection, but more than
5% of your addresses are marked as unknow than you must decrease number
of threads till optimum. Pay attention to cause of unchecked
address: the impossibility to connect with smtp-server or timeout point
to bad connection or channel overloading, and DNS refusal point that DNS-server
doesn't cope with program requests and number of threads must be less.
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6. Where can I get addresses of DNS-servers?
The access time to DNS-servers, which the program uses by default, is
2-3 seconds for some users. Apply to your Internet provider for its DNS-server
address, if you want to shorten this period till half a second. Windows
can get this information automatically sometimes. And most of providers
use this feature to guard user from superfluous settings. Since version
1.65, AMV tries to determine DNS settings by itself and show them in "Windows
DNS Settings" at "DNS" tab. You can also determine DNS-servers
addresses independently using IPCONFIG utility with key /ALL under Windows
NT, or using WINIPCFG utility under Windows 95 or Windows 98. That are
utilities of operation system.
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7.What is DNS cache for ?
The cache allows to shorten time for checking. The most of Web-accelerators
work using the same principle. The program saves mail servers addresses
for domain anybody.com into internal cache when checking address john@anybody.com
and extract addresses from internal cache without repeated connection
to DNS-server when checking address mary@anybody.com.
The cache is erased with every run of mailing list checking and may be
switched off in program settings.
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8. What is the maximum size of maillist for checking?
The maximum size of mailing list is 1.000.000 addresses. It is impossible
to enlarge size of mailing list now without change program interface and
loss a number of possibilities because the program keeps in RAM whole
mailing list and log of each address. If you have computer with small
RAM, e.g. 16MB, it is recommended to divide your mailing list into 5 lists
with 20.000 emails in each using special utility.
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10. What is the direct delivery?
This term means mail delivery straight to mail server of receiver omitting
provider mail server. Usually mail server's and mail domain's names differ
from each other, for example mail server smtp.anybody.com serves mail
domain anybody.com. The association between mail server and mail domain
is determinated in DNS (Domain Name Service). So, computer with address
anybody.com can have no mail server and mail domain smtp.anybody.com can
doesn't exist, although server smtp.anybody.com receives mail for domain
anybody.com. AMV has option which allows to check address mary@anybody.com
on server anybody.com, if any mail server have not been found in DNS for
this address. It is not recommended to use this option for mailing list
checking, because in this case some of nonexistent addresses will be not
marked. If computer anybody.com has no mail server, AMV cann't connect
with it and marks this address as unchecked, because the server may be
inaccessible temporarily and address cann't be marked as bad. This option
was made specially for cognitive purposes.
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11. Where can I get address of domain for HELO?
If you have no your own permanent domain (e.g. you have dynamically assigned
IP only), leave this field blank and the program determine it automatically.
If the program couldn't do it, localhost domain will be used. See HELO
line in the log file to know what domain is used by program. It is not
recommended to use anybody else's or nonexistent domain, because some
mail servers disconnect after such try. Write domain of proxy server in
this field if you work through Socks5 proxy-server. Because you will "talk"
with mail servers through proxy-server and they will "see" your
proxy-server address, but not your computer address.
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12. What address can/must I write in "MAIL FROM"
?
Use your real e-mail. Don't use fictional e-mail, because some mail servers
check mail domain of sender. It is not recommended also to use address
from server with free mail service (like usa.net) because some organizations
protect their users from spamers and anonymous hooligans and their servers
don't receive messages from such addresses. You may use default address
verify@pisem.net, but it is better
to replace it for your real address.
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13. What is the proxy for and how to configure AMV for
work through proxy ?
Usually in organizations there is only one computer with direct Internet
connection. Other computers work with Internet using that computer as
intermediary. In this case use a special software called proxy-server.
Such connection scheme is shown in picture 2. There are several incompatible
types of proxy-servers: http-proxy, ftp-proxy, socks5-proxy, realaudio-proxy
and etc.
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Pic.2. - Local area network (LAN) of organization.
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To work with AMV on Computer 2 (see picture 2) software of Socks5 proxy-server
must be installed on server. You must set in program settings the work
through proxy-server with address gate.mycompany.com. Socks5 proxy-server
is on 1080 tcp-port of server by default, but ask about it your network
administrator. Program works only through Socks proxy-server, don't set
3128 port with http-proxy or 3121 port with ftp-proxy.
Specify proxy-server domain as domain for HELO on SMTP tab in program
settings, because mail server see address of proxy-server, but not your
computer address, when working through proxy-server. Please, look at AMV
help system for details.
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14. How to save only existent/nonexistent/checked addresses
?
Specify which addresses (Exist/Bad/Unknown/Unchecked) must be saved in
output file on Filtering tab in program settings. All addresses, except
marked as "bad", are saved by default (i.e. Exist/Unknown/Unchecked).
You can change settings in Filtering after checking repeatedly and save
result into separate files with "bad", "existent"
ø "unchecked" addresses. Filtering settings is accessible from
dialog "Save As" since 1.61 version of program. Now you may
don't open window "Settings..." and make changes in "Filtering"
before each saving result. Dialog window is shown in picture 3.
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Pic.3. - Filtering in Save As dialog.
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