How do I support multiple ISP accounts (smarthost) in the Postfix SMTP client for relaying email? For example:
[a] user1@isp1.com must be relay via smtp.isp1.com.
[b] user1@isp2.com must be relay via smtp.isp2.com.
[c] me@mycorp.com must relay all my default email via smtp.mycorp.com.
Only Postfix version v2.3+ supports multiple ISP accounts via sender-dependent override for the global relayhost parameter settings. Open your main.cf file:
# vi /etc/postfix/main.cf
Add or modify the settings as follows:
smtp_sender_dependent_authentication = yes sender_dependent_relayhost_maps = hash:/etc/postfix/relayhost_map smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/passwd relayhost = [smtp.mycorp.com]:submission |
Create /etc/postfix/relayhost_map file:
# vi /etc/postfix/relayhost_map
Append configuration as follows (please note that default smtp.mycorp.com is not included) :
# Per-sender provider user1@isp1.com [smtp.isp1.com] user1@isp2.com [smtp.isp2.com] |
Create update /etc/postfix/passwd file as follows:
# Per-sender authentication
user1@isp1.com user1@isp1.com:password4isp1
user1@isp2.com user2@isp2.com:password4isp2
# Login for the default relayhost
[smtp.mycorp.com] defaultUsername:defaultPassword |
Save and close the file. Restart Postfix:
# postmap hash:/etc/postfix/passwd
# postmap hash:/etc/postfix/relayhost_map
# /etc/init.d/postfix reload
Where,
- smtp_sender_dependent_authentication = yes : Enable sender-dependent authentication in the Postfix SMTP client; this is available only with SASL authentication.
- sender_dependent_relayhost_maps = hash:/etc/postfix/sender_relay : A sender-dependent override for the global relayhost parameter setting. The tables are searched by the envelope sender address and @domain. A lookup result of DUNNO terminates the search without overriding the global relayhost parameter setting.
- smtp_sasl_auth_enable = yes : Enable SASL authentication in the Postfix SMTP client. By default, the Postfix SMTP client uses no authentication.
- smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd : SMTP client lookup tables with one username:password entry per remote hostname or domain, or sender address when sender-dependent authentication is enabled.
- relayhost = [mail.myisp.net]:submission : Setup default relay host.
10 comment
Previous I was tried this concept but it was not working
My scenarios adding multiple users with SMTP auth
With username and passwd
Am waiting for your reply.please scrap me or mail me
this is my email id : krisuresh001@gmail.com
Is this also supported on sendmail?
At first, thanks aslot for making this (almost) clear.
What I don’t understand is: If …
“[a] user1@isp1.com must be relay via smtp.isp1.com.
[b] user1@isp2.com must be relay via smtp.isp2.com.”
(so there is only user1 involved)
… then why is this line in /etc/postfix/passwd ?
“user1@isp2.com user2@isp2.com:password4isp2″
Where does user2 coming from all the sudden?!
Shouldn’t it be like this
“user1@isp2.com user1@isp2.com:password4isp2″
or do you just want to show, that the username on the “real” isp2.com has not necessarily to correspondent with the “local” user1?
Thanks for answering,
Coschuetzer
Global internet providers aim is to provide access that is effortless to utilize. They provide access that is as fast as you absolutely need it to be, and will work with the system you have.
This configuration works well for the relay of all emails in each domain. My question now is whether there is a Postfix configuration
allowing the relay emails sent only to ‘hotmail.com’ for each domain. That would solve my problem, because the only emails I am having
reception problems are with ‘hotmail.com’, others are working properly and I can send to my VPS server.
But, how to use a variable in /etc/postfix/passwd???
I want postfix to authenticate with my ISP using the sender email addres as login and a fixed password. For example
user1@isp.com user1@isp.com:alwayssamepass
user2@isp.com user2@isp.com:alwayssamepass
user3@isp.com user3@isp.com:alwayssamepass
…
But I don’t want to write thousands of users. I want something like:
*@isp.com $sender_address:alwayssamepass
Do you understand mem?
Did you figure it out, on how to avoid writing thousands of users?
Thank you, excellent guide!
I had the same issue that one website on a shared host had to use office365.com SMTP server. I was about to cry when reading the official Postfix documentation – it would take forever to process all the information there. With this guide I was able to solve the problem in a matter of an hour.
Do you know for what is this? if each user as his own provider and password?
# Login for the default relayhost
[smtp.mycorp.com] defaultUsername:defaultPassword
What do you mean with? for what if each user as his own smtp connection?
‘Login for the default relayhost’