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Email Questions Page 1

Email Questions
Page 2

• Email is resolving very slowly on my virtual server. What can I do to improve its performance?
• I can receive email, but I often receive timeout errors when I try to send.
• When trying to send email, I receive "No Socket Error" from my email program.
• How many email accounts can I host on my virtual server?
• Why are there so many emails sitting in my mail server's ~/usr/spool/mqueue directory, waiting to be sent?
• When trying to send email attachments I receive errors. Any ideas on what I can do to correct this?
• How do I setup my virtual server to page my pager whenever I get an email?

Q: Email is resolving very slowly on my virtual server. What can I do to improve its performance?
A: Check the mail queue, located in your /usr/spool/mqueue directory, using the following command:
ll ~/usr/spool/mqueue
You may see a display such as:
total 3
-rw------- 1 username vuser 1676 Nov 4 00:18 dfAAA19297
-rw------- 1 username vuser 4090 Nov 2 01:33 dfBAA01360
-rw------- 1 username vuser 532 Nov 4 02:48 dfCAA13672
When you send an email, one of three things can happen:
1) It can resolve to a mailbox and be successfully received by that mailbox so that its owner can download it at a later time.
2) It can bounce because the address does not resolve to a mailbox, or the mailbox is not accepting email (usually because it is full or the server is filtering email).
3) Finally, it can be "spooled" or "queued" in your /usr/spool/mqueue directory.
The /usr/spool/mqueue directory contains any email which has not been sent or received successfully by your virtual server. There are a variety of reasons why this can happen. If you send an email to a server with which a connection is currently not possible; or if the email resolution for a domain is not clear; or if load on either the sending or receiving server is too high to handle emails - then the server will queue the email, and try to resolve it again at a later time.
By default, most mail servers attempt to send a queued message every five hours; however, your virtual server is set to try every 30 minutes. Automated settings do not always work as well as attempting to manually clear the queue, however, and if you find many emails in this directory, you can attempt the virtual sendmail –q command.
The mail queue is designed to only keep messages for five days, after which time if the message has not resolved, it will be bounced back to the sender.

Q: I can receive email, but I often receive timeout errors when I try to send.
A: Check the pophash file in your ~/etc directory, using the following command:
wc ~/etc/pophash
You may see a display such as:
479 958 8902 /usr/home/username/etc/pophash
With PopAuth installed, every time you or one of your users checks email, the IP address is added to the pophash database, which is then used for verifying a valid user when sending. Anyone coming from an IP address in the pophash file is then able to send email through your virtual server, and every time you or one of your users attempts to send email, this file is checked to make certain the IP address is present. When you run wc ~/etc/pophash, the first number display, in this case "479" is the number of lines in the file, where there is one IP address per line. If there are hundreds, or even thousands of IP addresses to check, the longer it will take to send, and the greater the chance that your connection will time out.
You can also place this command in your cron file, with a line such as:
0 3 * * * vcleandb > /dev/null
This line will clear your pophash database at 3:00 a.m. every day (server time),
The second part of the command, "> /dev/null" is simply to prevent the cron task from emailing you every time it runs to let you know it was successful. Once you have cleared the pophash database, you will need to check email again before sending.

Q: When trying to send email, I receive "No Socket Error" from my email program.
A: Your ISP may be blocking outgoing traffic on port 25.
Some dialup providers use this method to prevent spam, by keeping anyone with their service from using an outside mail server to send email. You will want to contact your dialup provider to find out if this is the case. However, if this is occurring, you can either use a different ISP connection when sending email.

Q: How many email accounts can I host on my virtual server?
A: There is no limit to the number of POP3 accounts you can create. Realistically, however, you will run into limits in terms of account administration, since the accounts will be hosted on your server and therefore will take up space for the incoming mail. We recommend allocating 5 MB per account

Q: Why are there so many emails sitting in my mail server's ~/usr/spool/mqueue directory, waiting to be sent?
A: There are many reasons why ~/usr/spool/mqueue may fill with messages.
If sendmail is temporarily unavailable (because of excessive server activity, for example), messages will queue in ~/usr/spool/mqueue until such time as sendmail can handle the messages.
Although sendmail will handle the messages on its own, you can force sendmail to process the mail queue by entering the virtual sendmail -q command at your mail server's Telnet/SSH prompt.
If the destination email server is temporarily unavailable, or if there are other errors with an email message, the message may be deferred and remain in ~/usr/spool/mqueue until it can be sent.
To check for errors or to find out why a message has not been sent, type the virtual sendmail -q –v command at your mail server's Telnet/SSH prompt. This command will process the mail queue in verbose mode, so you can see any errors or other messages arising from sendmail.
Finally, you can safely delete any file that is over five days old, as sendmail will stop trying to send a message after five days of not being able to reach the destination mail server.

Q: When trying to send email attachments I receive errors. Any ideas on what I can do to correct this?
A: You may be attempting to download a file attachment too large for your mail to handle. Email was never designed for file transfer, and therefore doesn't accomplish this efficiently. If you would like to send a large file to someone, we would recommend uploading it to your Virtual Server and making it available for download through HTTP or FTP.
Remember  there will be at least two copies of any file attachments. If your virtual server does not have enough extra space to hold two copies of an email, it cannot be delivered, and if your virtual server does not have enough extra space to hold two copies of your mailbox, you cannot download the mail.

Q: How do I setup my virtual server to page my pager whenever I get an email?
A:  NOTE: This FAQ assumes that your paging provider provides email service for your pager. If you do not know your pager's email address, simply call your paging provider and ask them if they provide this service to you.
It is easy to setup your virtual server to page you whenever you get an email. Simply follow the steps below:
1) Create a generic account on your virtual server using the vadduser command.
2) Name the account something like 'user1' or 'pageme' or whatever you want.
3) Edit your ~/etc/aliases file, and add the alias you want everyone to use.  Example: Suppose your name is Jim and you have jim@mydomain.com set up. You would then have jim point to your user account, and to your pager's email address like so:
jim: user1,5555555@mobile.att.net
4) Exit your aliases file and run the vnewaliases command to make the changes take effect.

Email Questions Page 1