I'm not sure I understand your question. I don't use email for this process...I log into Constant Contact on the web, then they handle the email. And this isn't really related to the sending of email, since the issue appears when CREATING the email in the Constant Contact program.

Others are reporting problems using the space bar. I suggest you type your message in a text editor and copy and paste it into Constant Contact. Have you ruled out any problem with your keyboard?

https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration)

You can check for font issues.

You can right-click and select "Inspect" to open the built-in Inspector with this element selected.

• https://developer.mozilla.org/en-US/docs/Tools/Page_Inspector/How_to/Examine_and_edit_HTML

You can check in the Rules tab in the right panel in the Inspector what font-family is used for selected text. You can check in the Fonts tab in the right panel in the Inspector what font is actually used because Firefox might be using a different font than specified by the website.

• https://developer.mozilla.org/en-US/docs/Tools/Page_Inspector/How_to/Edit_fonts

I REALLY appreciate the suggestions from all of you...but unfortunately, none of them worked to solve the problem. Even after escalating the issue, Constant Contact has been unable to find the source of the problem; their only suggestion is to use Chrome. I really hate Chrome, but unless anyone has more suggestions, I guess I'll have no choice. Sigh.

...something weird is happening: in any text block I insert, all the words run together as if I'm not hitting the spacebar.

Can you tell whether this is a keystroke processing problem or a display problem -- if you select and copy what you typed and then paste it into a plain text editor or textarea form field, are the spaces there?

Is Constant Contact the only site that has this problem, i.e., composing email messages on a webmail site or using other "fancy" text editors are okay?

Nope: no matter where I paste the text (both Notepad and Word), the words still run together.

And yes: this ONLY happens with Constant Contact...everywhere else (including MailerLite) is fine.

Can you paste some text here as it is possible that there are zero-width spaces (U+200B ​) instead of regular spaces in the text ?

• https://en.wikipedia.org/wiki/Zero-width_space
• Lorem​Ipsum​Dolor​Sit​Amet​Consectetur​Adipiscing​

Lorem​
Ipsum​
Dolor​
Sit​Amet​
Consectetur​
Adipiscing​