MTA configuration 

The BACKCLICK MTA is an alternative way to send out e-mails without using an external SMTP Relay Server. This menu item can be found under System Administration. 

 

Abb. 17.1 - MTA - Konfiguration (Grundeinstellungen -> Auslieferungszustand) 

 

In addition to the normal sending mode, BACKCLICK also lets you use an internal mail transfer agent (MTA) for sending e-mails. Unlike the standard mode, this internal MTA does not need a connection to SMTP servers, but communicates directly with the recipients’ servers. This makes it possible to display considerably more detailed results of the actual delivery rate, since BACKCLICK directly evaluates the recipients’ responses. This means that fewer bounce e-mails will be returned. Only manual answers will appear in the return queue of the IMF when the internal MTA is in use. No more unnecessary attempts at delivery to inaccessible e-mail addresses will be initiated (5 xx faults) because these will be intercepted beforehand. During a routine sending, or when e-mails are in the queue administration, a switch between sending and saving modes is impossible. 

PLEASE NOTE: To guarantee the highest possible delivery rate and minimize the danger of getting blacklisted as a spammer we advise BACKCLICK users to enter all PTR, RDNS, and SPF Information for ALL of the systems connected to BACKCLICK! Also please note that there are NO mail engines on an application server (in case more than one server is in use). This is because the MTA needs all the resources of the system, and the presence of a mail engine would severely disturb the application server. The use of more than one server is recommended. 

PLEASE NOTE: Be sure to read this information carefully before before you begin configuring the MTA! 

 

17.1.1. Use of the MTA: 

Define whether the MTA or the standard sending mode should be used. 

 

• Default value: deactivated

 

17.1.2. Number of the DNS Fallback Server: 

To be able to deliver an e-mail correctly, you must know the MX entries of the receiving domain. THE DNS server of your provider will be used (default). If this server is not available, it is also possible to get the MX entries from the Open DNS servers, most of which are slower than the ones your provider uses. 

 

• Default value: 10
• Minimum value: 5
• Maximum value: 100

 

17.1.3. Number of e-mails per sending thread: 

The internal MTA sends out e-mails in parallel (see 17.1.4), in predefined packages. The size of the packages defines the number of e-mails that are assimilated in the sending process. The sum of the e-mails assimilated in parallel amounts to the multiplication of the values defined under 17.1.3 and 17.1.4 (in the default settings, the value is: 5,000). The higher this value, the higher the load factor of the server. The values are restricted for safety reasons. 

 

• Default value: 50
• Minimum value: 50
• Maximum value: 200

 

17.1.4. Number of sending threads: 

The number of sending processes that are running parallel is defined here (also see 17.1.3). 

 

• Default value: 50
• Minimum value: 50
• Maximum value: 200

 

17.1.5. Calling interval for repetition mode (only valid if 17.1.21 is activated): 

E-mails that could not been sent successfully at the first attempt will be put into the queue, which will be assimilated when the first sending process has been completed. The assimilation of the queue will only take up sending on a single mail engine. The smaller the queue, the higher the speed of the sending will be. This means that the more good addresses you have, the faster the sending will be. The sizes of the sending queues also depend on the number of addresses in your subscriber data base. 

 

• Default value: 1 Minute
• Minimum value: 1 Minute
• Maximum value: 30 Minutes

 

17.1.6. Activate debug output in the log files: 

In addition to the normal logging procedure, this function lets you find any faults or errors by offering additional information. It increases the size of the log files considerably, and should only be activated in case of problems with the system. 

 

• Default value: deactivated

 

17.1.7. Log level: 

Here is where you define which information is to be included in the output within the log files of the internal MTA. If no log-files are produced, you may deactivate this function (although it is not recommended). 

 

• Default value: normal

 

17.1.8. Maximum number of delivery attempts (only relevant if 17.1.21 is activated): 

Define the number of delivery repetitions of wrong e-mails here. This value is to be entered manually. 

 

• Default value: 25
• Minimum value: 1
• Maximum value: 500

 

17.1.9. Maximum storing period of log-file backups: 

If the log rotation as per 17.1.11 is activated, this value defines the number of days the log-file backups created under 17.1.11 should be saved. If this value is exceeded, the log files that are older than this value will be removed automatically. 

 

• Default value: 10 Days
• Minimum value: 1 Day
• Maximum value: 30 Days

 

17.1.10. Maximum duration of an attempted delivery (only relevant if 17.1.21 is activated): 

The duration of time between repeated attempts to send out the e-mails is defined here. 

 

• Default value: 8 hours
• Minimum value: 1 hour
• Maximum value: 48 hours

 

17.1.11. Maximum size of the log files using log rotation: 

The maximum size of log files is defined here. Once a log file reaches this size, log rotation will be initiated. The current log file will be stored (see 17.1.9), labeled with an easily understood file name, and saved in the system. A new log file will be created afterwards. 

 

• Minimum value: Log-Rotation deactivated
• Maximum value: 500 MB

 

17.1.12. Maximum duration of sending an e-mail using priority calculation (ms): 

BACKCLICK gives priority to a fast-working MX server, for the e-mails scheduled to be delivered. The faster the MX server, the faster the e-mails will be delivered. BACKCLICK therefore calculates an index of speed for every MX server used. Technical Explanation: The calculation of this speed index is based on the time a server needs to accept an e-mail of 10KB. This value will be saved in the database (in milliseconds). If an unknown MX server is added, the default value of 30,000 ms will be stored in the database. Using this value, the unknown MX server will be the last server on the priority list. While BACKCLICK is sending newsletters, the speed index will be calculated again. So, these servers will be automatically sorted into their proper places on the list after several sendings. The faster the receiving server, the sooner the e-mails will be sent and delivered to the subscriber. This value has to be entered manually in milliseconds. 

 

• Default value: 1000

 

17.1.13. Minimum size of an e-mail for the calculation of priority (in bytes): 

The minimum size of an e-mail needed for the calculation of priority is to be defined here. If you send out e-mails or newsletters with a smaller size than is defined here, no calculation of the speed index will be performed (see 17.1.12). This value is to be entered manually in bytes. 

 

• Default value: 3072 (3 KB)

 

17.1.14. Mode for the repetition of delivery attempts (only relevant if 17.1.21. is activated): 

There are three variants fixing how long or how often the delivery of faulty e-mails should be. attempted. The first possibility is stopping the repetition after a certain number of tries (see 17.1.8); the second possibility would be to stop the sending after a certain amount of time (see 17.1.10). The third possibility is a combination of the first two. Using this combination, BACKCLICK decides when the sending is stopped, depending on the condition that happens first. 

 

• Default value: Combination of number and time (what happens first).

 

17.1.15. Writing the log entries (every n e-mails): 

Define the number of newsletters after which the sending status of the e-mails should be stored in the database. 

 

• Default value: 500
• Minimum value: 100
• Maximum value: 2000

 

17.1.16. Writing the log entries in repetition mode (every n e-mails): 

Define the number of newsletters after which the sending status of the e-mails should be saved in the database (in repetition 

mode). 

 

• Default value: 500
• Minimum value: 100
• Maximum value: 2000

 

17.1.17. Timeout for server questions and answers: 

Enter the period of time a server is allowed to take until an answer, such as HELO, must be received. 

 

• Default value: 5 Seconds
• Minimum value: 1 Second
• Maximum value: 60 Seconds

 

17.1.18. Timeout for server questions and answers in repetition mode: 

Enter the period of time a server is allowed to take until an answer, such as HELO, must be received in repetition mode. 

 

• Default value: 30 Seconds
• Minimum value: 1 Second
• Maximum value: 60 Seconds

 

17.1.19. Timeout for the connection setup: 

The initial connection setup of a receiving server should not take longer than the amount of time defined here. 

 

• Default value: 5 Seconds
• Minimum value: 1 Second
• Maximum value: 60 Seconds

 

17.1.20. Timeout for the connection setup in repetition mode: 

The initial connection setup of a receiving server should not take longer than defined here in repetition mode. 

 

• Default value: 10 Seconds
• Minimum value: 1 Second
• Maximum value: 60 Seconds

 

17.1.21. Repetition of delivery when there are faults (Repetition Mode): 

This mode sets whether one or more delivery attempts should be done for e-mails that could not be delivered at the first dispatch attempt. If this option is deactivated, faulty delivery attempts are ignored, not stored in the queue and NOT delivered with that. 

 

• Default value: activated

 

If you have finished all of the settings, click on the -button to save them. This will be confirmed by the following message: 

 

To return to the default values, click on the -button. A separate window will be opened displaying this message: 

 

BACKCLICK MTA (optional Modul)