Red Hat Sendmail FAQ

Red Hat, Inc.

This document is meant to help new sendmail administrators with known problems, gotchas, and workarounds that can aid in getting the sendmail MTA installed and running on your Red Hat Linux system quickly and easily. We have attempted to document the most common issues and "gotchas" that arise. There is an important "sister document" to this FAQ, the Red Hat Sendmail HOWTO.

Table of Contents
1. Introduction
2. Preface
3. Installation & Initial Configuration Issues
3.1 I use a dial-up connection to send my mail. Why is my mail bouncing or getting rejected all the time?
3.2 My account at my ISP is but my account on my Linux box is `me'. I'm having trouble getting my e-mail to work right. It keeps going out as though it is from `me' instead of from `bobt'. How do I fix this?
3.3 I'm using procmail to filter my mail and I keep getting a message about a suspicious rcfile. What do I need to do?
3.4 I'm using fetchmail to get mail from my ISP account and sendmail keeps rejecting the mail. How do I fix this?
3.5 I decided to make changes to my macro configuration file with m4. When I rebooted, my changes were gone. What's going on?
3.6 Sending mail to a user in my domain I get an error message. It says, “config error. mail loops back to me (MX problem?)”. How do I fix this?
3.7 How do I route all mail to unknown users to a single account?
3.8 I need to act as a secondary MX for a friend of mine's domain, but inbound mail for that domain gets rejected. How do I make this work?
3.9 I have users on my local LAN who need to use my box as their MTA. When they send mail from their client software it bounces. How do I fix this?
3.10 Sendmail seems to be working fine, but when my users try to connect to the mailhost to POP their mail, they can't connect. What's wrong?
3.11 I upgraded to the sendmail 8.9.3 RPMs from Red Hat Linux 6.x and majordomo has basically quit working now. How do I fix it?
3.12 I have tried to set up the mailertable per the FM, but when I uncomment the mailertable line in I get: “/etc/ line 133: readcf: map mailertable: class dbm not available”. How do I fix this?
3.13 I'm using the rbl but there's one domain which is blocked that I want to allow. How do I do this?
3.14 I have always used .forward files and now I'm getting an error which says: “sh: procmail not available for sendmail programs”. How can I fix this?
3.15 I think I accidentally goofed up the permissions on some of sendmail's directories. How do I fix this?
3.16 Can I use sendmail 8.9.3 as either IMAP or POP3 server?
3.17 How can I set up an auto-responder?
3.19 Why does my sendmail process hang on boot up?
3.20 Why does my sendmail process sometimes hang when connecting over a SLIP/PPP link?
3.21 Why do I get the error message unable to write /etc/mail/
3.20 How do I set up aliases so that no matter what happens will be delivered to one person?
4. Advanced Issues
4.1 How can I foward e-mail and keep the message on the server too?
4.2 I don't need a full mailing list manager like majordomo, so what's the best way to create a simple newsletter system without it?
4.3 I don't have a file and I've never needed one. It's not in my macro config either, but something isn't right because some mail is not being accepted. How do I tell what sendmail thinks is in class w?
4.4 We had a user leave and are forwarding his mail, but we're still getting lots of mail for him. What can we do to let people know he's moved on?
4.5 I had a user leave recently and we forwarded his mail once he let us know where to send it, but he has 30 messages in his old mail spool which won't forward. How can we send him this mail at his new address?
4.6 I run a mass e-mail to some 40,000 customers every month. My file system gets hammered about 4 times during the mailing at about 10k each. I believe the problem is that mail got so stacked up in the queue, the kernel can't deal with it any longer.
4.7 How can I force a message in sendmail's mail queue to be delivered?
4.8 I keep getting the following errors: "collect: I/O error on connection" or "reply: read error from". What will fix this?
4.9 I keep getting error 552 `message to large'. How do I fix this?
4.10 My clients sometimes get 30 to 40 second delays when they try and send mail through our mailhost, but it works fine other than this delay. We've checked everything and there just doesn't seem to be anything obviously wrong with our configuration. What else should we check?
4.11 I'm running sendmail on my firewall or bastion host but I don't want my users accessing this machine to send and receive mail. The external MX records all point at the bastion host which works fine, but I want to configure a host on my internal network for my users to use to send and receive mail. How do I get the mail off of the bastion host and onto the internal host, and how do I still use the bastion host to route the mail?
4.12 I have a static IP, but I'm on a dial-up. My ISP pulls secondary MX for my domain. When I connect I can't seem to get mail. What should I do?
5. Additional Questions?
6. Additional References
6.1 Internet References
6.2 Published References
6.3 Local References