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Why perform mail checks? |
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Even if an email link is correctly written it should not be assumed that the link actually works. Moreover if there are multiple addresses which have not been checked then 5%, for example, of outbound emails may not be correctly sent or received.
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Why does my mail server fail with Access Denied? |
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Sitemorse tests all the mail servers listed for your domain, including the backup ones that are in general infrequently used. We can find hidden problems that only occasionally surface in normal use. However, in some cases an ISP deliberately blocks servers from talking to your mail servers, which can cause an Access Denied error message. Ask your ISP to un-block our servers IP addresses ('89.234.59.74' and '89.234.59.75'). Please note that during Sitemorse's testing, it talks to your mail servers, but it never actually sends any email through them. Thus, there is no need to block our servers - it would not result in you receiving any junk mail or test messages.
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Why does Sitemorse check my backup mail servers? |
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Any domain (the part after the '@' in your email address - e.g. 'sitemorse.com') which is used for email has one or more mail servers listed in the domain name system. For example: 'MX 10 a.mx.sitemorse.com.' 'MX 20 b.mx.sitemorse.com.' When someone else's mail server is trying to send you email, it generally tries your mail servers in priority order, lowest number first. In the example above, server 'a' is therefore the "primary" mail server, and server 'b' is a backup server. The important thing to note here is that which server is contacted is not under your control - any listed server may be contacted at any time. For example, a temporary network fault anywhere on the Internet between the sender and your mail server could mean that a backup server suddenly receives mail. If the primary server goes down or become unresponsive, the backup server(s) will immediately be required to handle all the mail for your domain. For these reasons, Sitemorse checks all the listed mail servers when it is testing an email address - backup mail servers will always be receiving a small percentage of the mail, and can at any time suddenly be receiving all the mail. If the backup server is misconfigured, you could be losing some of your mail all of the time - and if the primary server goes down, you could be losing all of your mail. Sitemorse helps you ensure that such a misconfiguration can be detected before it causes major problems.
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My mail server fails with "Too many concurrent SMTP connections" |
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Sitemorse only ever makes a single connection to a mail server, returning any error message encountered. If Sitemorse experiences an error during an email transaction there is every reason to believe a user would experience the same fault and be unable to send email. If this error references a backup (or secondary) mail server email will probably be delivered as expected to your domain. In the event the primary sever cannot be contacted a client will contact the backup server, and receive the error message. Every mail server advertised as accepting mail for your domain must be able to do so. The error message "Too many concurrent SMTP connections" is generated by the message transfer agent (MTA) running on the mail server. The popular MTA "EXIM" returns this message when under heavy load from all domains it accepts mail for. Capacity on such a mail server should be increased.
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Mail exceptions - MessageLabs' clients |
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Sitemorse testing of email addresses that are handled by MessageLabs often produces problem diagnostics. These are due to the way MessageLabs' servers handle mail transactions. We are not saying we agree with the outcome of our discussions, or the individual setup at MessageLabs we are merely seeking to explain why the errors occur. When an email is sent to your domain, the sending server uses the Domain Name System (DNS) to look up your mail servers. Usually, there are two or more servers listed, with associated priority values - typically a "primary" server and one or more "backup" servers. The DNS will always send mail to the primary server. The backup servers are there to accept email when and if the main server is unavailable for any reason, and to forward it on to the main server when it returns to service. The backup servers will, in a conventional setup, accept incoming email which they then forward to the primary server. This conventional setup allows Sitemorse to check that both the primary AND backup servers are available, functioning correctly and are configured correctly. Your primary and backup servers are integral parts of your email service which is why we check both of them. The servers that MessageLabs list in the Domain Name System as "backup" servers are not true mail servers. They never accept email, but simply always return a "temporary failure" error code. (this allows them to reduce the amount of Spam they have to handle) This error code is what is shown in the Sitemorse diagnostics. If you require further information, you should contact your MessageLabs account manager to discuss your specific setup.
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Why do some mailto addresses fail? |
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Sitemorse checks URLs for syntax and passes requests to the appropriate mail servers, stopping short of actually sending an email. If any error messages are received from the mail servers, they are recorded. As Sitemorse checks all mail servers for any given mailto: url, it may uncover problems that are not immediately apparent. Emails are passed to the first mail server that will accept them. The mail servers are prioritised such that the primary server gets the first opportunity to handle the mail, followed by the secondary then tertiary and so on. Therefore if there is a problem with the tertiary mail server it will remain unnoticed until there is, for example, a high volume of emails occupying the primary and secondary servers and emails fail to be delivered. Undelivered emails do not always raise immediate error messages to the sender and in most cases the recipient is completely unaware that emails are missing. It is not possible to check that an email address is functioning correctly simply by sending emails to it. |
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