NMS newsletters messed up

[leoteo]

Dear forum,

I have a problem with the messages sent out by NMS 2.7.4.
I am running CMSMS 1.11.9, CGJobMgr is 1.2.16, TinyMCE 2.9.10.1

It seems that at a particular character in the message, "something happens" on the way from the data base to the email. In some cases, a newline or space seems to be introduced, but I am not sure whether this is always the case.
In HTML messages, this can have serious consequences, since it can mess up tags. In my case, a <span... became <s pan..., so everything that followed was struck through. In the email message body, it seems a </s> was added at the end to close the <s ... tag (which was clearly not in the original message).

I checked with phpmyadmin that the message stored in table cms_module_nms_message_content is still perfectly fine (no space/newline). So, it must happen on the way from there to the final email.

Can this be related to some length limitations? Just to give an idea, in my case it seems to occur after about 5000 characters of the email. When I delete some character before <span, the "messing up" moves accordingly (meaning that <span will become, say, <spa n).

Has anybody experienced this issue? I am thankful for hints and suggestions.

Best,
leoteo