SMTP (smtp.domain.com), POP3 (mail.domain.com), MX
So help me put this into perspective.
SMTP is used to send mail from the inside of the company out to people on the Internet.
POP3 (often mail.domain.com) is used to receive mail from the people on the internet.
MX is used for... ??? Is it supposed to be the same as mail.domain.com or smtp.domain.com or what? =(
I have three servers (all in the same LAN, and all Linux).
The first two have public Internet IPs (static).
The third one cannot be communicated with from the Internet (no WAN static IP).
The first server receives and sends to the second server.
The second server sorts and forwards to the third server.
Third server ultimately delivers the mail to the employees.
(Or at least I think this is how it is setup.)
When I send an e-mail from the inside to myself, it says it's coming from the second server.
When I set smtp/mail.domain to the first server, and the MX to the first server, and I send an e-mail from the Internet to a company employee, I will get a reply back from the first server with this:
The original message was received at Fri, 22 Oct 2010 21:54:52 -0500
from mail-iw0-f178.google.com [209.85.214.178]----- The following addresses had permanent fatal errors -----
(reason: 553 5.3.5 system config error)----- Transcript of session follows -----
553 5.3.5 mail2.company.com. config error: mail loops back to me (MX problem?)
554 5.3.5 Local configuration error
The original message was received at Fri, 22 Oct 2010 21:55:41 -0500
from mail-vw0-f50.google.com [209.85.212.50]----- The following addresses had permanent fatal errors -----
(reason: 553 5.3.5 system config error)
(reason: 553 5.3.5 system config error)
(reason: 553 5.3.5 system config error)----- Transcript of session follows -----
554 5.3.5 Local configuration error
When I set smtp/mail.domain to the first server, and the MX to the second server, and I send an e-mail from the Internet to a company employee, I will receive no responses (nothing happens).
There is a private address that can only be accessed from the inside of the company that takes the employee to Squirrel Mail login (there are no public DNS records for this, so I assume one of the servers is acting as an inside DNS as far as this goes): intmail.company.com. When I ping it, the WAN static IP of the second server is what I get.
There is one employee who uses Outlook; everyone else must use Squirrel Mail. This employee is the CEO. His Outlook is setup to receive and send mail to/from the second server (by its internal LAN IP) on IMAP.
Please help me.
EDIT: Some DNS stuff on the company.com domain..
www A 3600
@ A 3600
* A 3600
mail2.company.com A 3600
server1.company.com A 3600
server2.company.com CNAME 3600 www.company.com
mail.company.com CNAME 3600
smtp.company.com CNAME 3600
MX 3600 10
Comments
-
The DNS MX record should be pointing to the SMTP server. When email gets sent out the email client(or associated server) looks at the @domain.com and does a dns lookup for the MX record for "domain.com". It then contacts port 25(SMTP) on the server specified by the MX record and sends the email through.
In your case if you have an internal and external SMTP server you will probably need to configure DNS for internal and external views. The internal zone will use an MX record for the internal SMTP server and the external zone will use an MX record pointing to the external/public SMTP server.0
Categories
- All Categories
- 61 LFX Mentorship
- 114 LFX Mentorship: Linux Kernel
- 618 Linux Foundation IT Professional Programs
- 322 Cloud Engineer IT Professional Program
- 141 Advanced Cloud Engineer IT Professional Program
- 56 DevOps Engineer IT Professional Program
- 67 Cloud Native Developer IT Professional Program
- 6 Express Training Courses
- 6 Express Courses - Discussion Forum
- 2.3K Training Courses
- 19 LFC110 Class Forum - Discontinued
- 9 LFC131 Class Forum
- 31 LFD102 Class Forum
- 178 LFD103 Class Forum
- LFD110 Class Forum
- 24 LFD121 Class Forum
- LFD133 Class Forum
- 2 LFD137 Class Forum
- 62 LFD201 Class Forum
- 2 LFD210 Class Forum
- 1 LFD210-CN Class Forum
- 1 LFD213 Class Forum - Discontinued
- 128 LFD232 Class Forum - Discontinued
- LFD233 Class Forum
- LFD237 Class Forum
- 23 LFD254 Class Forum
- 659 LFD259 Class Forum
- 108 LFD272 Class Forum
- 1 LFD272-JP クラス フォーラム
- 4 LFD273 Class Forum
- LFS101 Class Forum
- LFS116 Class Forum
- 2 LFS145 Class Forum
- 28 LFS200 Class Forum
- 740 LFS201 Class Forum - Discontinued
- 1 LFS201-JP クラス フォーラム
- 13 LFS203 Class Forum
- 98 LFS207 Class Forum
- 301 LFS211 Class Forum
- 54 LFS216 Class Forum
- 47 LFS241 Class Forum
- 41 LFS242 Class Forum
- 38 LFS243 Class Forum
- 12 LFS244 Class Forum
- LFS245 Class Forum
- 41 LFS250 Class Forum
- 1 LFS250-JP クラス フォーラム
- LFS251 Class Forum
- 143 LFS253 Class Forum
- LFS254 Class Forum
- LFS255 Class Forum
- 2 LFS256 Class Forum
- LFS257 Class Forum
- 1.2K LFS258 Class Forum
- 10 LFS258-JP クラス フォーラム
- 108 LFS260 Class Forum
- 147 LFS261 Class Forum
- 39 LFS262 Class Forum
- 83 LFS263 Class Forum - Discontinued
- 15 LFS264 Class Forum - Discontinued
- 11 LFS266 Class Forum - Discontinued
- 21 LFS267 Class Forum
- 18 LFS268 Class Forum
- 26 LFS269 Class Forum
- 204 LFS272 Class Forum
- 1 LFS272-JP クラス フォーラム
- LFS274 Class Forum
- 3 LFS281 Class Forum
- 258 LFW211 Class Forum
- 179 LFW212 Class Forum
- 9 SKF100 Class Forum
- SKF200 Class Forum
- 908 Hardware
- 221 Drivers
- 74 I/O Devices
- 44 Monitors
- 116 Multimedia
- 210 Networking
- 102 Printers & Scanners
- 86 Storage
- 765 Linux Distributions
- 88 Debian
- 66 Fedora
- 15 Linux Mint
- 13 Mageia
- 24 openSUSE
- 144 Red Hat Enterprise
- 33 Slackware
- 13 SUSE Enterprise
- 357 Ubuntu
- 483 Linux System Administration
- 40 Cloud Computing
- 70 Command Line/Scripting
- Github systems admin projects
- 95 Linux Security
- 80 Network Management
- 108 System Management
- 52 Web Management
- 75 Mobile Computing
- 25 Android
- 35 Development
- 1.2K New to Linux
- 1.1K Getting Started with Linux
- 544 Off Topic
- 131 Introductions
- 223 Small Talk
- 22 Study Material
- 836 Programming and Development
- 285 Kernel Development
- 517 Software Development
- 975 Software
- 261 Applications
- 185 Command Line
- 3 Compiling/Installing
- 119 Games
- 318 Installation
- 65 All In Program
- 65 All In Forum
Upcoming Training
-
August 20, 2018
Kubernetes Administration (LFS458)
-
August 20, 2018
Linux System Administration (LFS301)
-
August 27, 2018
Open Source Virtualization (LFS462)
-
August 27, 2018
Linux Kernel Debugging and Security (LFD440)