Okay... it took me a while to figure out what you were actually complaining about. I gather you view it as a problem that the string returned by "encode_base64()" contains a line-feed character at the end.

Is that really a problem? I'm actually not familiar with the relevant specs for base64, but this sort of behavior doesn't seem all that strange or surprising -- especially since there appears to be no trouble when "decode_base64()" is applied to the string returned by "encode_base64()"; the round-trip output matches the input:

muse MIME::Base64;
use strict;
use warnings;

my $teststr = "peip:930612";
my $testenc = encode_base64( $teststr );
my $testdec = decode_base64( $testenc );
die "ACK! MIME::Base64 is broke!\n" unless ( $testdec eq $teststr );
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Looks to me like you should expect a base64-encoded string to end with a line-feed character (or at least, this shouldn't be considered a bug). But I could be wrong, since I haven't read the spec for base64 encoding.

(Do you know from personal experience that other perl versions behave differently?)

update: Just tried this on 5.8.1 and 5.5.3, and noticed that the string returned by encode_base64() includes a final line-feed in all cases. Must be normal.