Step 3. Subject and content

  • Updated

Editing content

Content management system (CMS), the Optimizely template kit or HTML code: read about editing tools for your mailings in Editing message content.


Your mailing's subject line appears next to the sender address in the recipient's email program. The sender and subject most strongly influence a mailing's open rate. You should limit the subject's length, such as 45-60 characters, because some email programs might cut off longer lines.

Prefix or suffix subject line lets you automatically add a prefix or suffix to the subject line of any mailing.

Unicode characters

You can use Unicode characters in the subject line to increase the recipients' attention. Instead of using a plain text subject line, like NEW! Bikini "Malibu" now in the shop, you can enhance it with Unicode characters: NEW! Bikini "Malibu" now in the shop Image: Unicode characters.

At you can find a list of Unicode characters that are supported by most web browsers and email clients. Copy the desired symbol from the list and paste it into the subject line. Also set the character set to UTF-8 to display Unicode characters correctly. See Character set.

Unicode characters are displayed differently by different operating systems (iOS, Android, and so on) and email clients (Gmail, Outlook, and so on) Therefore, always send a test message to check the appearance before sending.

Content templates

The content of your mailing is created using content templates in Optimizely Campaign. Use the Free Text template if you create your mailings externally (outside of Optimizely Campaign), for example, through your agency or yourself using an HTML editor. This template lets you copy prepared text and HTML content directly.

However, if your mailings will have the same appearance (as is usually the case for newsletters), you can save time using specially-prepared content templates. The templates are designed to your specifications by Optimizely. Or, you can use the Template Kit.

Using content templates, you can create the content of your mailing using predefined modules. When creating a new mailing, just enter the text and upload images. Optimizely Campaign creates a completely formatted mailing. No knowledge of HTML is needed.

To use a template for your mailing, select it and click Edit.

About templates

See Designing a newsletter about email design using templates. Get tips and instructions for design and examples and suggestions from template developers.

Content attachments

To send attachments with a mailing, click the Attachments tab. If you have already sent mailings with attachments, the attachment files appear in the overview. To send one of these files as an attachment to the current mailing, select the check box next to the file description.

To send a new file as an attachment, follow these steps.

  1. Click New. The assistant for uploading attachment opens.
  2. Select whether to upload a file from your computer, or a URL that links to a file. If you choose Upload from hard drive, a copy of the file is created in the Optimizely Campaign server. If you choose Use URL, make sure that the file is available when the mailing is sent.
  3. Click Next.
  4. Click  Browse... and select the file to be uploaded. If you link a file using a URL, enter the full URL.
  5. Click Next.
  6. Complete the File name and Description boxes. Optimizely Campaign uses the name and description for internal management of the attachments, but not for the sending.
  7. Click  Save to make the file available as an attachment. After you upload or link the file, it appears in the list and can be sent as attachment for current and future mailings.

Special characters in file names of attachments

Do not use an umlaut and ß in the file name. Some email clients remove special characters from the file name. Nevertheless, the recipients can still open and save the attachments. Only the name is changed.

Do not delete files from the list of attachments even if they only were attached to a single mailing. If you delete the file from the file server, it will no longer be available to recipients when they open the email.

Send attachments in offline HTML mode

Attachments sent in this mode are loaded immediately upon receipt of the email. So, do not send large files in this mode, as this may delay the receipt of the email.

Due to a bug in the Apple email client, attachments sent in HTML offline mode do not appear in Apple Mail and on iPhones. If you send attachments in standard mode, there is no such problem.

Personalized Attachments

Use Personalized Attachments to send attachments to particular recipients. Before sending the email, you must transmit such attachments to  Optimizely Campaign using HTTP API. The uploaded attachments can be used when sending transaction emails. For example, you can send invoices and order confirmations to your recipients. See the HTTP API manual.

Character set

Use the drop-down list Character set ("Encoding") to select the character set to be used for encoding your mailing.

  • ISO-8859-1. For recipients in German-speaking, Western European and North American countries.
  • ISO-8859-2. For recipients in Central-South-Eastern Europe, for example in Poland, Croatia or Slovakia.
  • UTF-8. Supports most special characters of all languages. Select this encoding if you are writing to recipients in other regions of the world, such as Eastern Europe or Turkey.

Notes for print mailings

Select a template from the list and click Edit content. For technical reasons, you can only insert content in print mailings with a template. By default, Optimizely Campaign provides templates for the formats Letter DIN A4, Postcard DIN A6 and Postcard DIN lang.

For the different printing zones of a letter or postcard, there are restrictions regarding colors, fonts and background images. See Editing print message content.