Sending messages and related problems

Sending email Messages

Common SMTP server details configuration

Common disconnection errors troubleshooting

In order to send an email message you first need to specify the recipients and the sender.

The list of distribution lists (defined in Manage lists) is shown in the Select distribution list field. Select one and the addresses in the list will be used as recipients. Each contact will receive a personal email message.

The email message sender will be specified in the Sender e-mail address and Sender name fields. You can freely type in these fields or select an address and a name from the comboboxes, which display the last 10 names and addresses previously used in sending operations (the lists will be empty if no email has ever been sent). If a subscription/unsubscription address was provided to the selected distribution list, it will be automatically shown as the email sender address. However this is just default behavior, the address and/or the name can be manually changed.

You can also optionally specify a custom Reply-To email address: this is the address replies will be sent to. If it is left blank, replies will be sent to the sender address (this is the default behavior for personal e-mail messages).

To start sending email messages just click on the Send button. Obviously if it’s the first sending operation, or if the connection settings have changed, it will be necessary to first set up the Send settings, otherwise the message won’t be sent.

Two Email Send modes are available: Direct send and Use SMTP server.

  • By selecting Direct send the software will look for each recipient’s e-mail server and will automatically connect to it, therefore “skipping” the SMTP server that won’t then be needed in the send settings. To perform such search SendBlaster will use the currently selected default connection DNS, but it is also possible (and sometimes needed) to manually set a different DNS, by enabling the option Manually set DNS server and by typing the correct IP address. Keep in mind that certain e-mail domains (for instance, hotmail) don’t allow direct sends: the message gets rejected if it originates from a desktop system as opposed to a public SMTP server.
  • By enabling the Retry with SMTP in case of error, in case the message isn’t accepted by the recipient’s e-mail server, the software will try to deliver the message to the SMTP server, by using the Use SMTP server settings.
  • By selecting Use SMTP server, e-mail sending will take place just like in a standard e-mail client, that is, by delivering the message to one’s own ISP SMTP server.
  • It is necessary to specify the name of the SMTP server (which, may include port number in the “server:port” format) and, in case a user authentication is required, to select Authentication required and specify Username and Password. This parameters are the ones used in your e-mail client software, therefore all you’ll need to do is “copy” them from a working e-mail account (to make sure the SMTP server is reachable just click on the Connection test button). The SSL checkbox enables SSL communication, which may be needed by some SMTP servers (a typical example is Gmail’s SMTP server).
  • By enabling the Retry with direct send in case of error, in case the message isn’t accepted by the SMTP server, the software will try to deliver the message directly to the recipient’s e-mail server, by using the Direct send settings.


Use direct send or the SMTP server?

The choice depends, first of all, on the availability of a good SMTP server. If your ISP SMTP server is able to handle a lot of messages in a fast sequence or even sending messages simultaneously, using an SMTP server is faster and more reliable, since your SMTP server is “closer” to your computer than the single recipient’s e-mail server.

However, some providers try to prevent users from using the server for spamming purposes by imposing restrictions on the number of messages that can be sent within a specific time span and the number of messages that can be sent simultaneously. For instance, an SMTP server could accept no more than a message every 5 seconds and not allow sending more than 2 messages at a time. All messages that exceed these restrictions will be rejected with an error. This does not mean that the server or the software aren’t working properly, but rather, that it will be necessary to set up in a different way the sending timing option in the Advanced settings section.

In such cases, it could be faster and more convenient to use the direct send. The direct send requires a little more time to deliver each message (since it has to make a request to the DNS server and the e-mail server could be very “far” from the user’s PC), however this time increase is compensated by the possibility to send more messages simultaneously without having to add extra pauses between messages.

Direct send is also useful when a sending operation has to be performed using a connection without knowing the SMTP server (typically the case when using a notebook “away”, meaning not in the office or at home – common in the case of a public access wireless network).

The Advanced settings section allows you to fine-tune the sending timing. This is useful to perform a sending operation at the maximum possible speed allowed by the SMTP server antispam restrictions. Here’s the meaning of each option:

  • Pause between messages: the number of seconds elapsing between message sending.
  • Pause between blocks: the number of messages elapsing between each block of messages.
  • Messages per block: the number of messages sent in each block
  • Timeout: the maximum number of seconds after which the message sending is aborted
  • Connections: the maximum number of simultaneous connections, meaning the number of messages simultaneously sent*.
  • Further attempts in case of error: If the SMTP server or the recipient’s server (for a direct send) doesn’t accept the message, the software can wait a certain number of seconds and retry sending the message one or more times.
  • Pause between attempts: the number of seconds of delay before retrying to send an unaccepted message.

The right configuration cannot be set before a few attempts, verifying the number of messages that actually get delivered. To simplify the settings, some Suggested settings are available. They might not be optimized for your connection but can be considered a good starting point to get the best configuration.

Warning: Distribution lists can contain invalid e-mail addresses, or some e-mail servers may be temporarily inactive. Therefore, when using lists that contain a great deal of addresses it should be considered normal and inevitable that, despite the chosen sending mode and the settings, not all messages will get delivered and a certain percentage will return an error. In such case it will be possible to try to complete the sending operation at a later time using the history functions.


How can I get the right advanced settings?

To get the right advanced settings it’s necessary to try out different combinations (normally a list with about 10 addresses will suffice) and verify how many messages actually get delivered (this info is given at the end of the sending operation, when it is also possible to check the logs). Users connected to a “tolerant” enough SMTP server won’t probably experience many problems, regardless of the settings specified that will only effect the sending speed.

On the other hand, if your connection is to a rather “strict” STMP server, in order to be able to deliver a high number of messages it might be necessary to slow down message sending and avoid sending messages simultaneously.

Here’s a few simple rules worth considering:

  • A tolerant SMTP server allows fast sending without pauses (or limited pauses anyway). On rather restricted SMTP servers that use numerous antispam filters, raise pauses and lower simultaneous connections.
  • Normally, SMTP servers don’t allow sending many messages simultaneously, therefore when using the SMTP mode the number of connections must be low or, in certain situations, equal to 1 (no simultaneous connections). If the SMTP server is equipped with antispam restriction mechanisms, it may be necessary to slow down message sending by setting a pause of a few seconds between each send, and set a longer pause between message blocks. Also, blocks shouldn’t contain more than a few dozen messages.
  • In case of a direct send, with a standard distribution list containing addresses belonging to different domains, the messages will be delivered to a variety of different servers: it is therefore possible to set a high number of connections* and limited (or none at all) pauses between messages and between blocks.
  • Raising the number of attempts in case of error can raise the percentage of success but it will slow down the sending operation, particularly if the number of simultaneous connections is low. Completing the operation at a later time from the history window (after having waited a few minutes) can be considered good practice.

Amongst the advance settings you can also find the message Encoding mode: choose between quoted-printable and base64. The header content that shows the software that generated the message (the Xmailer text): by using the Default setting the header will include SendBlaster’s name and release. Otherwise you can type a fee text, to simulate sending through a different e-mail client or choose the None option to avoid having a header added to the message.

Domain option allows for customizing the machine name used by the software for connecting to SMTP server or recipients’ email servers. This can be useful when using Direct send: some servers verify domain name before accepting messages; they require that domain name corresponds to the public hostname on the network, and before accepting messages they perform a ping (or similar operation) in order to verify that domain name corresponds to the IP address of the machine requesting connection. Should this be the case, selecting Internet address may lower refused messages. We suggest using default settings, or using Internet address when direct sending and PC local name when using SMTP (SMTP servers usually don’t perform any particular check on domain name).
SendBlaster checks your machine’s public address each time it is started; should Internet connection not be available when starting, public address may be left empty and PC local name will be used instead. If a fixed public IP is available, experienced users will select User defined… and enter a fixed value (please note that a hostname is needed – not an IP address) – but keep in mind that a wrong setting could compromise successful sending.

*In the Free edition the maximum number of connections is 2, even if a higher number is specified.